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1
Hidayat, Wahyu, David P. Sahara, Sri Widiyantoro, Suharsono Suharsono, Ridho Kresna Wattimena, Sari Melati, I. Putu Raditya Ambara Putra, Septian Prahastudhi, Eric Sitorus, and Erwin Riyanto. "Testing the Utilization of a Seismic Network Outside the Main Mining Facility Area for Expanding the Microseismic Monitoring Coverage in a Deep Block Caving." Applied Sciences 12, no. 14 (July 19, 2022): 7265. http://dx.doi.org/10.3390/app12147265.
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In the case of mining in an inclined intrusion using the block caving method, the highest stress is usually concentrated in the seismogenic and abutment zones, especially in the front of the sloping area. In an inclined intrusion of more than 40°, the seismometer network is usually distributed in the facility area where the footwall area is also located. This causes a limitation in microseismic monitoring due to ray coverage. In this study, we conduct a seismometer deployment outside a mining facilities area with borehole seismometers. The study aims to maximize the resolution and minimize the monitoring uncertainty of underground mines. We created two scenarios of seismometer deployment: (i) seismometers are deployed following the intrusion mining level in the mining facility area; and (ii) additional seismometers are deployed in off-facilities areas. Both areas were tested for their raypath responses and sensitivity using the Checkerboard Resolution Test (CRT). The monitoring resolution influenced by the additional borehole seismometers in the off-facilities area can be quantified. The results suggest that the additional seismometers in the off-facilities areas can increase resolution by 30% in the seismogenic and abutment zones.
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Zheng, Xichen, Deyong Chen, Junbo Wang, Jian Chen, Chao Xu, Wenjie Qi, and Bowen Liu. "Microelectromechanical System-Based Electrochemical Seismometers with Two Pairs of Electrodes Integrated on One Chip." Sensors 19, no. 18 (September 13, 2019): 3953. http://dx.doi.org/10.3390/s19183953.
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This paper presents microelectromechanical system (MEMS)-based electrochemical seismometers with two pairs of electrodes integrated on one chip. Both theoretical analysis and numerical simulations were conducted to reveal the working principle of the proposed electrochemical seismometers, finding that flow holes distributed on cathodes rather than anodes can produce significantly higher sensitivities. The proposed electrochemical seismometers were fabricated based on conventional micromachined processes with high fabrication repeatability. Sensitivity measurements of the proposed seismometers and their commercial counterpart of CME6011 were conducted, indicating the sensitivities of the proposed seismometer with flow holes on cathodes were two orders higher than the counterpart with flow holes on anodes and one order higher than CME6011 at dominant frequencies. Measurements of random ground motions based on the proposed seismometer with flow holes on cathodes and CME6011 were conducted, producing comparable noise levels without observable ground motions and high correlations in response to random events of ground motions. These results validated the functionality of the proposed electrochemical seismometers, which may contribute to seismic monitoring in the near future.
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Rodgers, Peter W. "Frequency limits for seismometers as determined from signal-to-noise ratios. Part 2. The feedback seismometer." Bulletin of the Seismological Society of America 82, no. 2 (April 1, 1992): 1099–123. http://dx.doi.org/10.1785/bssa0820021099.
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Abstract The range of frequencies that a seismometer can record is nominally set by the corner frequencies of its amplitude frequency response. In recording pre-event noise in very quiet seismic sites, the internally generated self-noise of the seismometer can put further limits on the range of frequencies that can be recorded. Some examples of such low seismic noise sites are Lajitas, Texas; Deep Springs, California; and Karkaralinsk, U.S.S.R. In such sites, the seismometer self-noise can be large enough to degrade the signal-to-noise ratio (SNR) of the recorded pre-event data. The widely used low seismic noise model (LNM) (due to Peterson, 1982; Peterson and Hutt, 1982; Peterson and Tilgner, 1985; Peterson and Hutt, 1989) is used as representative of the input ground motion acceleration power density spectrum (pds) at such very low noise sites. This study determines the range of frequencies for which the SNR of a feedback seismometer exceeds 3 db (a factor of 2 in power and 1.414 in amplitude). Analytic expressions for the SNR are developed for three types of feedback seismometers. These are the displacement feedback, velocity feedback, and coil-to-coil velocity feedback seismometers. It was found that the analytic SNRs of the displacement and velocity feedback seismometers are identical and that the SNRs for the coil-coil feedback seismometer and the electromagnetic seismometer are also the same. The signal pds using Peterson's LNM as an input is developed for each of the three types of feedback seismometers. Suspension noise is modeled following Aki and Richards (1980). In order to model the electronically caused component of the self-noise, the electronic noise properties of two commonly used operational amplifiers (Precision Monolithics OP-27 and the Burr-Brown OPA2111 FET) are described. Using these, noise models are developed for a synchronous demodulator and a chopper-stabilized amplifier. These noise models are used to numerically compute the SNRs for the two feedback seismometers used as examples, which are the Guralp Systems CMG-3ESP and Sprengnether Instruments SBX-1000 feedback seismometers. For each of the example seismometers, the calculated range of frequencies for which their SNR exceeds 3 db is as follows: the CMG-3ESP, 0.025 to 13.3 Hz; the SBX-1000, 0.098 to 11.3 Hz. The calculated and measured SNRs for the CMG-3ESP are compared. The calculated upper frequency for a SNR of 3 db was 13.3 Hz compared with 18.4 Hz measured in the noise tests. The calculated lower frequency for a SNR of 3 db was 0.025 Hz, whereas the measured value was 0.047 Hz. The difference is most likely due to the fact the CMG-3ESP is cut off at 0.1 Hz. Formulas are developed in Appendix A for calculating the SNR and self-noise of identical, colocated seismometers from their recorded outputs. The analytic transfer functions, midband gain, upper and lower corner frequencies, and bandwidths for the three types of feedback seismometers are given in Appendix B for comparison with the frequency limits set by the SNR.
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Costley, Richard D., Sarah McComas, Christopher Simpson, Chris Hayward, and Mihan McKenna. "Seismometers as infrasound sensors." Journal of the Acoustical Society of America 155, no. 3_Supplement (March 1, 2024): A72—A73. http://dx.doi.org/10.1121/10.0026848.
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An experiment was conducted in West-Central Mississippi in which five explosive charges were detonated. The TNT equivalent sizes of the charges ranged from 0.57 to 10.91 kg (1.25 to 24 lb). Among the arrays of sensors deployed, seismometers were deployed near microphones at distances of 0.5, 2.1, and 8.4 km from the source. The blast wave at these distances had decayed in amplitude to an acoustic wave. The coherence between the seismometer and microphone signals showed that the seismometer provided reasonable representation of the acoustic wave over limited frequency bands; however, these bands changed between sensor locations. In addition, two 3-component seismometers were deployed near each other 8.4 km from the source. These seismometers were of different types, one having a resonance frequency of 1 Hz and the other at 4.5 Hz. The signals from the horizontal components of these seismometers were analyzed to determine their effectiveness as vector sensors. The results showed that the back-azimuth determined from the seismometers agreed reasonably well with ground truth for the first arrival of the acoustic wavefront; however, the results degraded as the trailing part of the wavefront passed. Permission to publish was granted by the Director, Geotechnical and Structures Laboratory.
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Chui, Talso C. P., Andrew Erwin, and Inseob Hahn. "Extensions of the Galperin Transformation Matrices for Triaxial Seismometers." Sensors 23, no. 1 (December 20, 2022): 26. http://dx.doi.org/10.3390/s23010026.
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Since its invention in 1955, the Galperin symmetric triaxial seismometer has been widely used for seismic detection on Earth, and most recently on the planet Mars. In this paper, we present detailed physics of such seismometers, which has not yet been published in open literature. We extended Galperin’s original work, which is based on idealized geometry and assumptions, to include more practical cases, including (1) non-idealized tilt angles of its component seismometers; (2) component seismometers that are not exactly oriented 120° apart; (3) distributed mass on the boom; and (4) the case of operations at lower frequencies.
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Qi, Kun, Yao-Yao Xu, Xiao-Bing Deng, Le-Le Chen, Qin Luo, Min-Kang Zhou, Xiao-Chun Duan, and Zhong-Kun Hu. "Influence of magnetic field on the seismometer in vibration correction for atom gravimeters." Review of Scientific Instruments 93, no. 4 (April 1, 2022): 044503. http://dx.doi.org/10.1063/5.0081148.
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Vibration correction provides a simple and flexible method of suppressing ambient vibration noise in transportable atom gravimeters. However, in the seismometers used for vibration correction, a spurious output may be induced by the magnetic field of the magnetic–optical trap, introducing errors to the gravity measurements. This paper evaluates the influence of the magnetic field on the seismometer and the corresponding errors in the gravity measurements. It is found that an error level of order 10 μGal may be present if the seismometer is not configured carefully. The dependence of the influence on the orientation of the seismometer and the lasting time of the magnetic field are investigated. The effective suppression of the influence by shielding the seismometer is also demonstrated. Our results focus attention on the possible errors related to seismometers in high-precision gravity measurements by using atom gravimeters.
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Erwin, Andrew, Leandro A. N. de Paula, Nicholas C. Schmerr, David Shelton, Inseob Hahn, P. Roger Williamson, Ho Jung Paik, and Talso C. P. Chui. "Brownian Noise and Temperature Sensitivity of Long-Period Lunar Seismometers." Bulletin of the Seismological Society of America 111, no. 6 (November 2, 2021): 3065–75. http://dx.doi.org/10.1785/0120210072.
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ABSTRACT As long-period ground motion holds the key to understanding the interior of the Earth’s Moon, reducing long-period noise sources will be an essential area of focus in the design of future lunar seismometers. For the proposed Lunar Geophysical Network (LGN), the International Lunar Network (ILN) Science Definition Team specifies that an LGN enabling seismometer will need to be more sensitive than any previous seismometer at frequencies below 1 Hz. In an effort toward lowering the seismometer noise floor for lunar geophysical missions, we evaluate the 1/f Brownian noise and the temperature sensitivity of a seismometer. Temperature sensitivity of a seismometer is related to an important component of the seismometer output noise that is proportional to the temperature noise in the environment. The implications of the ILN requirement are presented in the context of the state-of-the-art InSight Seismic Experiment for Interior Structure (SEIS) Very Broad Band (VBB) planetary seismometer. Brownian noise due to internal friction was estimated for future lunar operation after accounting for the rebalance of the product of mass and distance to the center of gravity of the pendulum for the SEIS-VBB sensor. We find that Brownian noise could be a limiting factor in meeting the ILN requirement for lunar seismometers. Further, we have developed a formalism to understand the temperature sensitivity of a seismometer, relating it quantitatively to the local gravity, the thermoelastic coefficient of the spring, change in center of gravity, and the coefficient of thermal expansion of the mechanical structures. We found that in general the temperature sensitivity of a seismometer is proportional to the local gravity, and so the temperature sensitivity can be reduced when operating on a planetary body with lower gravity. Our Brownian noise and temperature sensitivity models will be useful in the design of the next generation of planetary seismometers.
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Wang, Kaiming, Wenyi Li, Lijun Zhao, Daxin Yu, and Shaogang Wei. "Research on Self-Noise Characteristics of Nine Types of Seismometers Obtained by PDF Representation Using Continuous Seismic Data from the Malingshan Seismic Station, China." Sensors 23, no. 1 (December 22, 2022): 110. http://dx.doi.org/10.3390/s23010110.
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The self-noise level of a seismometer can determine the performance of the seismic instrument and limit the ability to use seismic data to solve geoscience problems. Accurately measuring and simultaneously comparing the self-noise models from different types of seismometers has long been a challenging task due to the constraints of observation conditions. In this paper, the self-noise power spectral density (PSD) values of nine types of seismometers are calculated using four months of continuous seismic waveforms from Malingshan seismic station, China, and nine self-noise models are obtained based on the probability density function (PDF) representation. For the seismometer STS-2.5, the self-noise levels on the horizontal channels (E–W and N–S) are significantly higher than that on the vertical channel (U–D) in the microseism band (0.1 Hz to 1 Hz), which is a computing bias caused by the misalignment between the sensors in the horizontal direction, while the remarkably elevated noise on the horizontal channels at the low frequencies (<0.6 Hz) may originate from the local variation of atmospheric pressure. As for the very broadband seismometers Trillium-Horizon-120 and Trillium-120PA, and the ultra-broadband seismometers Trillium-Horizon-360 and CMG-3T-360, there is a trade-off between the microseism band range and low-frequency range in the PSD curves of the vertical channel. When the level of self-noise in the microseism band is high, the self-noise at low frequencies is relatively low. Although compared with the other very broadband seismometers, the self-noise level of the vertical component of the STS-2.5 is 3 dB to 4 dB lower at frequencies less than 1 Hz, the self-noise level of the STS-2.5 at high frequencies (>2 Hz) is slightly higher than others. From our observations, we conclude that the nine seismometers cannot reach the lowest noise level in all frequency bands within the working range.
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Marusiak, Angela G., Nicholas C. Schmerr, Daniella N. DellaGiustina, Brad Avenson, S. Hop Bailey, Veronica J. Bray, Juliette I. Brodbeck, et al. "The Deployment of the Seismometer to Investigate Ice and Ocean Structure (SIIOS) in Northwest Greenland: An Analog Experiment for Icy Ocean World Seismic Deployments." Seismological Research Letters 92, no. 3 (March 17, 2021): 2036–49. http://dx.doi.org/10.1785/0220200291.
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Abstract In anticipation of future spacecraft missions to icy ocean worlds, the Seismometer to Investigate Ice and Ocean Structure (SIIOS) was funded by National Aeronautics and Space Administration, to prepare for seismologic investigations of these worlds. During the summer of 2018, the SIIOS team deployed a seismic experiment on the Greenland ice sheet situated, approximately, 80 km north of Qaanaaq, Greenland. The seismometers deployed included one Trillium 120 s Posthole (TPH) broadband seismometer, 13 Silicon Audio flight-candidate seismometers, and five Sercel L28 4.5 Hz geophones. Seismometers were buried 1 m deep in the firn in a cross-shaped array centered on a collocated TPH and Silicon Audio instrument. One part of the array consisted of Silicon Audio and Sercel geophones situated 1 m from the center of the array in the ordinal directions. A second set of four Silicon Audio instruments was situated 1 km from the center of the array in the cardinal directions. A mock-lander spacecraft was placed at the array center and instrumented with four Silicon Audio seismometers. We performed an active-source experiment and a passive-listening experiment that lasted for, approximately, 12 days. The active–source experiment consisted of 9–12 sledgehammer strikes to an aluminum plate at 10 separate locations up to 100 m from the array center. The passive experiment recorded the ice-sheet ambient background noise, as well as local and regional events. Both datasets will be used to quantify differences in spacecraft instrumentation deployment strategies, and for evaluating science capabilities for single-station and small-aperture seismic arrays in future geophysical missions. Our initial results indicate that the flight-candidate seismometer performs comparably to the TPH at frequencies above 0.1 Hz and that instruments coupled to the mock-lander perform comparably to ground-based instrumentation in the frequency band of 0.1–10 Hz. For future icy ocean world missions, a deck-coupled seismometer would perform similarly to a ground-based deployment across the most frequency bands.
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Tape, Carl, Adam T. Ringler, and Don L. Hampton. "Recording the Aurora at Seismometers across Alaska." Seismological Research Letters 91, no. 6 (July 29, 2020): 3039–53. http://dx.doi.org/10.1785/0220200161.
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Abstract We examine three continuously recording data sets related to the aurora: all-sky camera images, three-component magnetometer data, and vertical-component, broadband seismic data as part of the EarthScope project (2014 to present). Across Alaska there are six all-sky cameras, 13 magnetometers, and >200 seismometers. The all-sky images and magnetometers have the same objective, which is to monitor space weather and improve our understanding of auroral activity, including the influence on magnetic fields in the ground. These variations in the magnetic field are also visible on seismometers, to the extent that during an auroral event, the long-period (40–800 s) waves recorded by a seismometer are magnetic field variations, not true ground motion. Although this is a problem—one that can be rectified with magnetic shielding at each seismometer site—it is also an opportunity because the present seismic array in Alaska is much broader than the coverage by magnetometers and all-sky cameras. Here we focus on three aurora events and document a direct link between aurora images in the night sky and seismometer recordings on ground. Simultaneous recordings by magnetometers provide a critical link between the sky images and the seismometer recordings. We document qualitative correlations among sky, magnetic, and seismic data. The findings suggest that the signature of auroral activity is widespread across seismometers in Alaska, implying that the seismic array could be used to enhance the spatial resolution of the existing network of all-sky cameras and magnetometers. Future efforts to improve the multisensor seismic stations in Alaska, for the purpose of monitoring seismic and auroral activity, should consider installation of all-sky cameras, installation of magnetometers, and magnetic shielding of seismic sensors.
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Ringler, A. T., J. Steim, D. C. Wilson, R. Widmer-Schnidrig, and R. E. Anthony. "Improvements in seismic resolution and current limitations in the Global Seismographic Network." Geophysical Journal International 220, no. 1 (October 21, 2019): 508–21. http://dx.doi.org/10.1093/gji/ggz473.
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SUMMARY Station noise levels play a fundamental limitation in our ability to detect seismic signals. These noise levels are frequency-dependent and arise from a number of physically different drivers. At periods greater than 100 s, station noise levels are often limited by the self-noise of the instrument as well as the sensitivity of the instrument to non-seismic noise sources. Recently, station operators in the Global Seismographic Network (GSN) have deployed several Streckeisen STS-6A very broad-band borehole seismometers. These sensors provide a potential replacement for the no-longer-produced Streckeisen STS-1 seismometer and the GeoTech KS-54 000 borehole seismometer. Along with showing some of the initial observational improvements from installing modern very broad-band seismometers at depth, we look at current limitations in the seismic resolution from earth tide periods 100 000 s (0.01 mHz) to Nyquist at most GSN sites (0.02 s or 50 Hz). Finally, we show the potential for improved observations of continuously excited horizontal Earth hum as well as the splitting of very long-period torsional modes. Both of these observations make use of the low horizontal noise levels which are obtained by installing very broad-band borehole seismometers at depth.
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Ringler, A. T., and R. E. Anthony. "Local Variations in Broadband Sensor Installations: Orientations, Sensitivities, and Noise Levels." Pure and Applied Geophysics 179, no. 1 (November 11, 2021): 217–31. http://dx.doi.org/10.1007/s00024-021-02895-9.
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AbstractAs seismologists continue to place more stringent demands on data quality, accurately described metadata are becoming increasingly important. In order to better constrain the orientation and sensitivities of seismometers deployed in U.S. Geological Survey networks, the Albuquerque Seismological Laboratory (ASL) has recently begun identifying true north with a fiber optic gyroscope (FOG) and has developed methodologies to constrain mid-band, vertical component sensitivity levels to less than 1% in a controlled environment. However, questions remain regarding the accuracy of this new alignment technique as well as if instrument sensitivities and background noise levels are stable when the seismometers are installed in different environmental settings. In this study, we examine the stability and repeatability of these parameters by reinstalling two high-quality broadband seismometers (Streckeisen STS-2.5 and Nanometrics T-360 Global Seismographic Network (GSN) version) at different locations around the ASL and comparing them to each other and a reference STS-6 seismometer that stayed stationary for the duration of the experiment. We find that even in different environmental conditions, the sensitivities of the two broadband seismometers stayed stable to within 0.1% and that orientations attained using the FOG are generally accurate to within a degree. However, one install was off by 5° due to a mistake made by the installation team. These results indicate that while technology and methodologies are now in place to calibrate and orient a seismometer to within 1°, human error both during the installation and while producing the metadata is often a limiting factor. Finally, we find that background noise levels at short periods (0.1–1 s) become noisier when the sensors are emplaced in unconsolidated materials, whereas the noise levels at long periods (30–100 s) are not sensitive to local geological structure on the vertical components.
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Rodgers, Peter W. "Maximizing the signal-to-noise ratio of the electromagnetic seismometer: The optimum coil resistance, amplifier characteristics, and circuit." Bulletin of the Seismological Society of America 83, no. 2 (April 1, 1993): 561–82. http://dx.doi.org/10.1785/bssa0830020561.
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Abstract This study finds the optimum coil resistance, rc.opt, which maximizes the signal-to-noise ratio (SNR) of an electromagnetic (EM) seismometer and amplifier combination. The optimum coil resistance is shown to be the product of a seismometer factor (SF) times the noise resistance, Rn, of the amplifier. The seismometer factors range from 1.13 to 3.66 for the nine EM seismometers considered. The minimum noise figure solution, in which the amplifier noise resistance is set equal to the coil resistance, is shown to correspond to the special case in which there is no damping resistor present. It is also shown that the optimum form for the noise resistance is a constant independent of frequency and that this feature can be approximated with FET-like components such as the MAT-02. Examples of using rc.opt are given using both the 5500-ohm and the 500-ohm 1-Hz L4-C seismometers paired with the OP-27 and LT1028 operational amplifiers, respectively. It is pointed out that, although the resulting amplitude signal-to-noise ratios (ASNRs) are approximately equal, it is best to choose the seismometer-amplifier pair having the larger generator constant because it results in a larger signal. Furthermore, if the coil resistance is not the optimum value, the resulting decrease in the ASNR is less if the coil resistance is chosen greater than the optimum rather than less. The deleterious effects of mismatching seismometer and amplifier are shown by comparing ASNRs for the GS-13 seismometer paired with three different amplifiers. The degradation in ASNR is found to be as large as a factor of 3. It is pointed out that mismatching would not be done purposely but can inadvertently occur when connecting an EM seismometer to a seismic recorder whose input noise resistance properties are unknown, as in generally the case. It is recommended that manufacturers of seismic recorders obtain the necessary input noise data from the component manufacturers and supply the input noise resistance to users. Finally, the three commonly used single-ended preamplifier circuits used for EM seismometers are compared in terms of their resulting ASNRs. The same seismometer and amplifier are used in all three circuits. For the GS-13/MAT-02 pair, the noninverting, parallel damping resistor circuit resulted in an ASNR that was 3.8 times larger than that for the inverting, parallel damping resistor circuit, and 3 times larger than that for the inverting, series damping resistor circuit.
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Nakamichi, Haruhisa, Yoshiharu Hirayama, Toshiharu Ikeda, Hiroshi Ando, and Keiji Takeuchi. "A Half-Year Long Observation at Sakurajima Volcano, Japan Using a Multi-Channeled Seismometer System with Phase-Shifted Optical Interferometry." Journal of Disaster Research 17, no. 5 (August 1, 2022): 670–82. http://dx.doi.org/10.20965/jdr.2022.p0670.
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The performance of a multi-channel seismometer system with phase-shifted optical interferometry was improved by newly introduced sensors and a processing unit. The current version of the system consists of three optical wired seismometers and the unit. We deployed the system at Sakurajima Volcano and successfully operated it from June to December 2019. As the Sakurajima Volcano frequently erupts, a number of eruption events were observed during the observation period, as were a number of lightning strikes. In this study, we evaluated the observation performance of the volcanic earthquake and the noise caused by the lightning, using the spectrum and amplitude of the waveform. The results show that this sensor can observe earthquakes caused by eruptions as well as ordinary seismometers do. When the lightning struck, pulsed noise with power in a wide frequency band was observed in the existing seismometer, but not in the new sensor. Therefore, the observation was not affected by lightning. In addition, this system was found to be effective in the array analysis of volcanic earthquakes.
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Tikhotskiy, Sergey, Irina Bayuk, and Nikita Dubinya. "On the Possibility of Detecting Pore Pressure Changes in Marine Sediments Using Bottom Seismometer Data." Journal of Marine Science and Engineering 11, no. 9 (September 15, 2023): 1803. http://dx.doi.org/10.3390/jmse11091803.
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This paper is devoted to the detection and analysis of overpressure zones in unconsolidated seafloor sediments using an ocean-bottom seismometer. The methodological aspects of creating a system of anomalous pore pressure zone detection in marine sediments are studied. The aim of this study is to establish the requirements for a pore pressure monitoring system necessary to successfully detect overpressure zones based on seismic response, and to analyze temporal changes in pore pressure distribution. Data from a certain offshore field are used as a basis from which to construct synthetic models of overpressure distribution in marine sediments. Synthetic models are constructed using specially developed rock physics models for unconsolidated saturated media. Seismic responses are calculated for these synthetic models to represent data that otherwise would be obtained from bottom seismometers placed on the seafloor. Resultant seismic responses are studied with respect to the detection of overpressure zones. Possibilities and limitations of bottom seismometer data are discussed. Requirements for the frequency bands of bottom seismometers are formulated based on the results that are obtained.
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Marusiak, Angela G., Nicholas C. Schmerr, Daniella N. DellaGiustina, Erin C. Pettit, Peter H. Dahl, Brad Avenson, S. Hop Bailey, et al. "The Deployment of the Seismometer to Investigate Ice and Ocean Structure (SIIOS) on Gulkana Glacier, Alaska." Seismological Research Letters 91, no. 3 (March 18, 2020): 1901–14. http://dx.doi.org/10.1785/0220190328.
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Abstract The Seismometer to Investigate Ice and Ocean Structure (SIIOS) is a NASA-funded analog mission program to test flight-candidate instrumentation on icy-ocean world analog sites. In September 2017, an SIIOS experiment was deployed on Gulkana Glacier. The instrumentation included a Nanometrics Trillium 120 s Posthole seismometer, four Nanometrics Trillium Compact (TC) seismometers, four Mark Products L28 geophones, and five each of Silicon Audio (SiA) 203P-15 and 203P-60 seismometers. The SiA sensors served as our flight-candidate instruments. The instrumentation was arranged in a small (<2 m) aperture array with most sensors deployed in the ice. We also placed five of the SiA seismometers on top of a mock lander to simulate placement on a lander deck. The instrumentation recorded an active-source experiment immediately after deployment and then passively for 13 days. We conducted an active-source experiment using a sledgehammer striking an aluminum plate at 13 locations, with 9–13 shots occurring at each location. During the passive observation, the experiment recorded one large Mw 7.1 event that occurred in Mexico and four other teleseismic events with Mw>6.0. The active- and passive-source signals are being used to constrain the local glacial hydrological structure, environmental seismicity, to develop algorithms to detect and locate seismic sources, and to quantify the similarities and differences in science capabilities between sensors. Initial results indicate the flight-candidate instrumentation performs comparably to the Trillium Posthole up to periods of 3 s, after which the flight-candidate performs more comparably to the TCs.
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Rodgers, Peter W. "Self-noise spectra for 34 common electromagnetic seismometer/preamplifier pairs." Bulletin of the Seismological Society of America 84, no. 1 (February 1, 1994): 222–28. http://dx.doi.org/10.1785/bssa0840010222.
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Abstract Because of a lack of such information, computed self-noise spectra are presented for a total of 34 frequently used electromagnetic-seismometer/preamplifier combinations. For convenience, most of these data are given in three sets of units. Peterson's Low Noise Model is included on each plot for comparison. The self noises of nine frequently employed electromagnetic seismometers properly matched to their operational amplifier (op-amp) preamplifiers are plotted. In terms of amplitude density spectra in (m/sec**2)/Hz**0.5, the values of the self-noise spectra at resonance range from a low of 3 × 10−10 for the GS-13 to a high of 1.3 × 10−8 for the HS-1. Between these two seismometers, in order of increasing noise at resonance, are the SV-1, SL-210V, S-13, SS-1, L-4C, S-6000CD, and the L-22D. To show which seismometers exhibit the lowest noise with which operational amplifier preamplifiers, the self noises of the HS-1, L-22D, L-4C, GS-13, SV-1, and SL-210V are plotted each paired with four commonly used op-amps: the LT1028, OP-227, OP-77, and the LT1012. For the GS-13, the LT1012 was the quietest. For the rest, the OP-227 was the best. For a given seismometer, the differences in self noise between op-amps were frequently a factor of 2 or 3, and as large as 10 in one case. The use of these op-amps in the analog front ends of five current digital seismic recorders is discussed.
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Fauvel, Kevin, Daniel Balouek-Thomert, Diego Melgar, Pedro Silva, Anthony Simonet, Gabriel Antoniu, Alexandru Costan, et al. "A Distributed Multi-Sensor Machine Learning Approach to Earthquake Early Warning." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 01 (April 3, 2020): 403–11. http://dx.doi.org/10.1609/aaai.v34i01.5376.
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Our research aims to improve the accuracy of Earthquake Early Warning (EEW) systems by means of machine learning. EEW systems are designed to detect and characterize medium and large earthquakes before their damaging effects reach a certain location. Traditional EEW methods based on seismometers fail to accurately identify large earthquakes due to their sensitivity to the ground motion velocity. The recently introduced high-precision GPS stations, on the other hand, are ineffective to identify medium earthquakes due to its propensity to produce noisy data. In addition, GPS stations and seismometers may be deployed in large numbers across different locations and may produce a significant volume of data consequently, affecting the response time and the robustness of EEW systems.In practice, EEW can be seen as a typical classification problem in the machine learning field: multi-sensor data are given in input, and earthquake severity is the classification result. In this paper, we introduce the Distributed Multi-Sensor Earthquake Early Warning (DMSEEW) system, a novel machine learning-based approach that combines data from both types of sensors (GPS stations and seismometers) to detect medium and large earthquakes. DMSEEW is based on a new stacking ensemble method which has been evaluated on a real-world dataset validated with geoscientists. The system builds on a geographically distributed infrastructure, ensuring an efficient computation in terms of response time and robustness to partial infrastructure failures. Our experiments show that DMSEEW is more accurate than the traditional seismometer-only approach and the combined-sensors (GPS and seismometers) approach that adopts the rule of relative strength.
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Cysela, R. Y., T. Setiawan, and Fatkhan. "Design of Borehole Seismometer Based on MEMS Accelerometer." Journal of Physics: Conference Series 2243, no. 1 (June 1, 2022): 012040. http://dx.doi.org/10.1088/1742-6596/2243/1/012040.
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Abstract Conventional seismometers use coil as the main sensor. Coil is relatively cheap, but in order to cover low frequency range, it becomes frail and has inappropriate a sampling rate. To overcome the limitation of conventional seismometers we use a MEMS sensor. The sensor is made from glass and silicon substrate which has no harmonic frequency characterization. It enables covering wide bandwidth with low frequency cover and high sampling rate response with high sensitivity. The usage of MEMS in electronics such as disk drive heads and inkjet printer heads. MEMS sensor also is used in different domains which include medical, automotive, communications and defence. This paper described a borehole seismometer that was composed of a MEMS accelerometer colibrys 1500SN. An arduino micro controller. Based on data calibration and physical simulation, MEMS sensor offers the potential to reduce costs while improving data quality.
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Calais, E., S. Symithe, T. Monfret, B. Delouis, A. Lomax, F. Courboulex, J. P. Ampuero, et al. "Citizen seismology helps decipher the 2021 Haiti earthquake." Science 376, no. 6590 (April 15, 2022): 283–87. http://dx.doi.org/10.1126/science.abn1045.
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On 14 August 2021, the moment magnitude ( M w ) 7.2 Nippes earthquake in Haiti occurred within the same fault zone as its devastating 2010 M w 7.0 predecessor, but struck the country when field access was limited by insecurity and conventional seismometers from the national network were inoperative. A network of citizen seismometers installed in 2019 provided near-field data critical to rapidly understand the mechanism of the mainshock and monitor its aftershock sequence. Their real-time data defined two aftershock clusters that coincide with two areas of coseismic slip derived from inversions of conventional seismological and geodetic data. Machine learning applied to data from the citizen seismometer closest to the mainshock allows us to forecast aftershocks as accurately as with the network-derived catalog. This shows the utility of citizen science contributing to our understanding of a major earthquake.
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Stähler, S. C., K. Sigloch, K. Hosseini, W. C. Crawford, G. Barruol, M. C. Schmidt-Aursch, M. Tsekhmistrenko, J. R. Scholz, A. Mazzullo, and M. Deen. "Performance report of the RHUM-RUM ocean bottom seismometer network around La Réunion, western Indian Ocean." Advances in Geosciences 41 (February 2, 2016): 43–63. http://dx.doi.org/10.5194/adgeo-41-43-2016.
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Abstract. RHUM-RUM is a German-French seismological experiment based on the sea floor surrounding the island of La Réunion, western Indian Ocean (Barruol and Sigloch, 2013). Its primary objective is to clarify the presence or absence of a mantle plume beneath the Reunion volcanic hotspot. RHUM-RUM's central component is a 13-month deployment (October 2012 to November 2013) of 57 broadband ocean bottom seismometers (OBS) and hydrophones over an area of 2000 × 2000 km2 surrounding the hotspot. The array contained 48 wideband OBS from the German DEPAS pool and 9 broadband OBS from the French INSU pool. It is the largest deployment of DEPAS and INSU OBS so far, and the first joint experiment. This article reviews network performance and data quality: of the 57 stations, 46 and 53 yielded good seismometer and hydrophone recordings, respectively. The 19 751 total deployment days yielded 18 735 days of hydrophone recordings and 15 941 days of seismometer recordings, which are 94 and 80 % of the theoretically possible yields. The INSU seismic sensors stand away from their OBS frames, whereas the DEPAS sensors are integrated into their frames. At long periods (> 10 s), the DEPAS seismometers are affected by significantly stronger noise than the INSU seismometers. On the horizontal components, this can be explained by tilting of the frame and buoy assemblage, e.g. through the action of ocean-bottom currents, but in addition the DEPAS intruments are affected by significant self-noise at long periods, including on the vertical channels. By comparison, the INSU instruments are much quieter at periods > 30 s and hence better suited for long-period signals studies. The trade-off of the instrument design is that the integrated DEPAS setup is easier to deploy and recover, especially when large numbers of stations are involved. Additionally, the wideband sensor has only half the power consumption of the broadband INSU seismometers. For the first time, this article publishes response information of the DEPAS instruments, which is necessary for any project where true ground displacement is of interest. The data will become publicly available at the end of 2017.
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Wen, Yi, Kang Wu, and Li-Jun Wang. "Analysis of vibration correction performance of vibration sensor for absolute gravity measurement." Acta Physica Sinica 71, no. 4 (2022): 049101. http://dx.doi.org/10.7498/aps.71.20211686.
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Absolute gravity measurement refers to the measurement of the absolute value of gravitational acceleration (<i>g</i>, approximately 9.8 m/s<sup>2</sup>). The precision of absolute gravity measurement is limited mainly by vibration noises. Vibration correction is a simple and feasible way to deal with vibration noises, which corrects the measurement results by detecting vibration noises with a sensor. At present, the vibration correction performance of different sensors lacks systematic analysis and evaluation. In this paper, the theoretical analysis of how the sensor characteristics affect the correction performance is carried out. The vibration correction performances of three sensors, two different seismometers and one accelerometer, are evaluated experimentally in the three cases with different vibration noises. The experimental results show that the correction precision obtained by using low-noise seismometer is limited mainly by its bandwidth and range. In case I i.e. the quiet environment, the standard deviation of corrected results obtained by using both seismometers can reach tens of μGal (1 μGal = 10<sup>–8</sup> m/s<sup>2</sup>), which is close to that obtained by using an ultra-low-frequency vibration isolator. However, in case II i.e. the noisy environment, the standard deviation of corrected results obtained by both seismometers increase to hundreds of μGal due to the enhancement of high-frequency vibration components. This means that the correction performances of both seismometers deteriorate, and the performance of seismometer with narrower bandwidth turns even worse. Moreover, two seismometers cannot even work in case III with stronger vibration noises due to the range limitation. On the other hand, the correction precision obtained by using accelerometer is affected mainly by its resolution which is on the order of mGal (1mGal = 10<sup>–5</sup> m/s<sup>2</sup>). Its bandwidth can reach hundreds of or even thousands of hertz and its range is generally over ±2 g, which is large enough to meet the needs for noisy and dynamic applications. In case I, the standard deviation after correction with accelerometer is larger than that before correction. This is because the intensity of vibration noises in this case is close to or even smaller than the self-noise of accelerometer so that it could not be detected effectively by accelerometer. In case II, the resolution of accelerometer is sufficient to detect the vibration noises effectively. The standard deviation of the results is reduced from 2822 μGal to 1374 μGal after correction with accelerometer, and equal to a precision of 0.1 mGal after 100 drops. In case III where the amplitude of vibration noise rises to 0.1 m/s<sup>2</sup> and seismometer cannot work, the accelerometer could still achieve a precision of 0.3 mGal after 100 drops. The systematic deviation is corrected from –1158 mGal to –285 μGal and the standard deviation is reduced from 34 mGal to 3.3 mGal. Therefore, the low-noise seismometer is more suitable for vibration correction in a quiet environment with stable foundation, which could realize a standard deviation superior to hundreds of μGal, while the accelerometer is more appropriate for vibration correction in a complex or dynamic environment, which could achieve a standard deviation of mGal-level. Finally, the present results and analysis provide a theoretical guidance for selecting and designing the sensors in vibration correction applications.
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Rodgers, Peter W., Aaron J. Martin, Michelle C. Robertson, Mark M. Hsu, and David B. Harris. "Signal-coil calibration of electromagnetic seismometers." Bulletin of the Seismological Society of America 85, no. 3 (June 1, 1995): 845–50. http://dx.doi.org/10.1785/bssa0850030845.
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Abstract We show that electromagnetic (em) seismometers may be easily and accurately calibrated by removing a step of current from their signal coil, and simultaneously switching the signal coil to a recorder to capture the response. A theory is developed that obtains the damped generator constant, resonant frequency, and damping ratio from the output of a system identifier used to analyze the response. Only the seismometer mass (from the manufacturer) and the applied current (measured) need be known for a complete calibration. The coil and damping resistances are not required. The method is confirmed by comparing this signal-coil method with weight-lift and calibration-coil calibrations. For a GS-13 V seismometer, these results were within 1.3% of each other. The undamped generator constant computed from the damped generator constant obtained by the signal-coil method matched the generator constant given by the manufacturer to better than 1%. Calibration of nine new L-4C components resulted in undamped generator constants all within 3% of the values given by the manufacturer. The circuit used in the signal-coil method is shown and explained.
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Il’inskiy, D. A., A. A. Ginzburg, V. V. Voronin, O. Yu Ganzha, A. B. Manukin, and K. A. Roginskiy. "Towards а design of new generation digital seismic seabed seismographs – current state and future outlook." Геоэкология. Инженерная геология. Гидрогеология. Геокриология, no. 2 (May 18, 2019): 87–101. http://dx.doi.org/10.31857/s0869-78092019287-101.
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The paper presents the comparative characteristics of self-pop-up digital seabed seismometers that have been developed since the early 2000s. The requirements for the main technical characteristics that should be considered for developing the new-generation of self-pop-up seabed seismometers have been proposed. The microcontroller and reference frequency generator are the key parts for a seabed seismometer design. The paper provides the development results of these key components, which are essential for the seismometer performance (power consumption and functionality).
A draft proposal for seabed seismic exploration project in the Russian sector of the Black Sea solving the current actual geological problems is presented. Implementation of the project will contribute to determination of the crystalline basement depth within the Shatsky ridge and the Tuapse depression; detection of P and S wave velocities in the lower part of sedimentary cover and in the basement, and to the refinement of the Earth’s crust thickness. The extension of regional seabed seismic lines from the Turkish to the Russian sector of the Black Sea will give the scientists a clearer picture of the Earth’s crust structure over the whole east Black Sea basin. The results of seabed studies will verify and improve the results of the Black Sea 2011 towed-streamer survey (with 10 km streamer) on the sedimentary cover structure and the Earth’s crust.
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Tague, John A., and Kerry D. Schutz. "Seismic transient deconvolution with model‐based signal processing." GEOPHYSICS 62, no. 4 (July 1997): 1321–30. http://dx.doi.org/10.1190/1.1444234.
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Short duration seismic disturbances, obscured by earth noise and distorted by the seismometers used to measure them, can be reconstructed using model‐based signal processing. “Model based” means that mathematical models of the seismic transient, earth noise, and seismometer dynamics are infused into the signal processor that estimates the disturbance. The processor imposes no predetermined structure on the transient and the earth noise need not be white. Model‐based processors produce good quality estimates for a broad class of transient waveforms.
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Rodgers, Peter W. "Frequency limits for seismometers as determined from signal-to-noise ratios. Part 1. The electromagnetic seismometer." Bulletin of the Seismological Society of America 82, no. 2 (April 1, 1992): 1071–98. http://dx.doi.org/10.1785/bssa0820021071.
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Abstract The range of frequencies that a seismometer can record is nominally set by the corner frequencies of its amplitude frequency response. In recording pre-event noise in very quiet seismic sites, the internally generated self-noise of the seismometer can put further limits on the range of frequencies that can be recorded. Some examples of such low seismic noise sites are Lajitas, Texas; Deep Springs, California; and Karkaralinsk, U.S.S.R. In such sites, the seismometer self-noise can be large enough to degrade the signal-to-noise ratio (SNR) of the recorded pre-event data. The widely used low seismic noise model (LNM) (due to Peterson, 1982; Peterson and Hutt, 1982; Peterson and Tilgner, 1985; Peterson and Hutt, 1989) is used as representative of the input ground motion acceleration power density spectrum (pds) at such very low noise sites. This study determines the range of frequencies for which the SNR of an electromagnetic seismometer exceeds 3 db (a factor of 2 in power and 1.414 in amplitude). In order to do this, an analytic expression is developed for the SNR of a generalized electromagnetic seismometer. The signal pds using Peterson's LNM as an input is developed for an electromagnetic seismometer. Suspension noise is modeled following Usher (1973). In order to determine the electronically caused component of the self-noise, noise properties are compared among three commonly used amplifiers. The advantages and disadvantages of the inverting and noninverting configurations in terms of their SNR are discussed. In most cases, the noninverting configuration is to be preferred as it avoids the use of the large gain setting resistances required in the inverting configuration to avoid loading the seismometer output. A noise model is developed for a typical low noise operational amplifier (Precision Monolithics OP-27). This noise model is used to numerically compute the SNRs for the three electromagnetic seismometers used as examples. The degradation in SNR caused by large gain setting resistances is shown. Numerical examples are given using the Mark Products L-4C and L-22D and the Teledyne Geotech GS-13 electromagnetic seismometers. For each of the example seismometers, the calculated range of frequencies for which their SNR exceeds 3 db is as follows: the GS-13, 0.078 to 56.1 Hz; the L-4C, 0.113 to 7.2 Hz; and the L-22D, 0.175 to 0.6 Hz. For the GS-13, the calculated lower and upper frequencies at which the SNR is 3 db are 0.078 and 56.1 Hz. This compares with the values 0.073 and 59 Hz measured in the noise tests on the vertical GS-13. Expressions for the total noise voltage referred to the input of an operational amplifier are developed in Appendix A. It is shown that in the inverting configuration, although no noise current flows in the input resistor, the noise current appears in the expression for the total noise voltage as if it did. In Appendix B, it is shown that any noise current flowing through an electromagnetic seismometer having a generator greater than several hundred V/m/sec generates a back emf that adds significantly to the noise of the system. This implies that system noise tests that substitute a resistor at the noninverting input of the preamplifier or clamp the seismometer mass will tend to underestimate the system noise.
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KINOSHITA, Shigeo. "Negative Feedback Seismometers." Zisin (Journal of the Seismological Society of Japan. 2nd ser.) 50, no. 4 (1998): 471–83. http://dx.doi.org/10.4294/zisin1948.50.4_471.
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Rong, Chao, Dingfan Zhang, Yuwen Cao, and Zhengbin Li. "Analyze the Difference Between Rotational and Translational Motions Produced by High-speed Train." Journal of Physics: Conference Series 2651, no. 1 (December 1, 2023): 012141. http://dx.doi.org/10.1088/1742-6596/2651/1/012141.
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Abstract The development of fiber optic gyroscope technology makes it possible to directly measure the rotational ground-motion. The joint observation of the three-component rotational seismometer and the traditional three-component translational seismometer is a trend of future. In this paper, the translational and rotational signals generated during the high-speed trainway are studied, and the three-component translational and rotational seismometers are fixed together to realize the joint recording of the high-speed trainway signal. Comparing the translational and rotational three-component data, we find that only one component waveforms and the spectrum have certain consistency. However, the difference between them indicates that the rotation and translation signals generated by the shallow surface wave signal have different frequency bands.
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Teisseyre, Krzysztof P., Michał Dudek, Leszek R. Jaroszewicz, Anna T. Kurzych, and Leopold Stempowski. "Study of Rotational Motions Caused by Multiple Mining Blasts Recorded by Different Types of Rotational Seismometers." Sensors 21, no. 12 (June 15, 2021): 4120. http://dx.doi.org/10.3390/s21124120.
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Digging two vertical shafts with the multiple blasts technique gave the opportunity to measure the induced angular motions in a horizontal plane with well-defined positions of sources. Three kinds of rotation rate sensors, sharing an underground location, were used. Two of them—a Fiber-Optic System for Rotational Events & phenomena Monitoring (FOSREM) and a prototypical seismometer housing the liquid-filled torus—sensed the rotation, while a microarray of two double-pendulum seismometers sensed both the rotation and symmetric strain. The FOSREM was sampled at 656.168 Hz, while all the others were only sampled at 100 Hz. There were considerable differences within the results gathered from the mining blasts, which should be attributed to two causes. The first one is the difference in principles of the operation and sampling rates of the devices used, while the other is the complex and spatially variable character of the studied wave fields. Additionally, we established that the liquid-filled sensor, due to its relatively low sensitivity, proved to be viable only during a registration of strong ground motions. Overall, a comparative study of three different rotational seismometers was performed during mining-induced strong ground motions with well-localized sources.
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Huang, Ching-Jer, Hsin-Yu Chen, Chung-Ray Chu, Ching-Ren Lin, Li-Chen Yen, Hsiao-Yuen Yin, Chau-Chang Wang, and Ban-Yuan Kuo. "Low-Frequency Ground Vibrations Generated by Debris Flows Detected by a Lab-Fabricated Seismometer." Sensors 22, no. 23 (November 29, 2022): 9310. http://dx.doi.org/10.3390/s22239310.
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A lab-fabricated ocean bottom seismometer was modified and deployed terrestrially to detect low-frequency (<10 Hz) ground vibrations produced by debris flows. A frequency–response test of the new seismometer revealed that it can detect seismic signals at frequencies of 0.3–120 Hz. Its seismic ground motion detection ability was investigated by comparing its measurements of seismic signals produced by rockfalls with those of a geophone. Two new seismometers were deployed at the Aiyuzi Stream, Nantou County, Taiwan, in September 2012. Seismic signals produced by two local earthquakes, two teleseisms, and three debris flows detected by the seismometer in 2013 and 2014 were discussed. The seismic signal frequencies of the local earthquakes and teleseisms (both approximately 1800 km apart) were 0.3–30 and <1 Hz, respectively. Moreover, seismometer measurements revealed that seismic signals generated by debris flows can have minimum frequencies as low as 2 Hz. Time-matched CCD camera images revealed that debris flow surge fronts with larger rocks have lower minimum frequencies. Finally, because the seismometer can detect low-frequency seismic waves with low spatial decay rates, it was able to detect one debris flow approximately 3 min and 40 s before it arrived.
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de Paula, Leandro A. N., Ronald S. Norton, Ho Jung Paik, Nicholas C. Schmerr, Paul R. Williamson, Talso C. P. Chui, and Inseob Hahn. "High-Sensitivity Seismometer Development for Lunar Applications." Sensors 23, no. 16 (August 18, 2023): 7245. http://dx.doi.org/10.3390/s23167245.
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Lunar seismology is a critical area of research, providing insights into the Moon’s internal structure, composition, and thermal history, as well as informing the design of safe and resilient habitats for future human settlements. This paper presents the development of a state-of-the-art, three-axis broadband seismometer with a low-frequency range of 0.001–1 Hz and a target sensitivity over one order of magnitude greater than previous Apollo-era instruments. The paper details the design, assembly, methodology, and test results. We compare the acceleration noise of our prototype and commercial seismometers across all three axes. Increasing the test mass and reducing its natural frequency may further improve performance. These advancements in seismometer technology hold promise for enhancing our understanding of the Moon’s and other celestial bodies’ internal structures and for informing the design of future landed missions to ocean worlds.
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Costley, Richard D., Chris Hayward, and Luis De Jesus Diaz. "Seismometers as infrasound sensors." Journal of the Acoustical Society of America 150, no. 4 (October 2021): A215. http://dx.doi.org/10.1121/10.0008163.
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Roberts, Peter M. "A versatile equalization circuit for increasing seismometer velocity response below the natural frequency." Bulletin of the Seismological Society of America 79, no. 5 (October 1, 1989): 1607–17. http://dx.doi.org/10.1785/bssa0790051607.
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Abstract A versatile and easily implemented circuit is described that increases the velocity amplitude response of seismometers below their natural frequency in order to extend the useful bandwidth to lower frequencies. The circuit employs a simple design that counteracts the ω2 rolloff of the seismometer by cascading two one-pole active low-pass filters in series. The low-pass stages are each summed with the unfiltered signal to maintain a flat unity amplitude response near and above the natural frequency. The design, testing, and field implementation are described for a version of the circuit used with Mark Products L4-C 1.0 Hz seismometers. The design produced a nominally flat response extending down to 0.1 Hz with tolerable stability over a wide range of ambient temperatures. Design procedures are described so that the circuit may be easily modified for any arbitrary natural frequency and range of desired equalization. The circuit can be installed very easily in nearly any recording equipment with minimal modification of existing circuitry. An example is shown of the measured and theoretical amplitude and phase responses for an existing seismic event recorder with and without the equalization circuit installed. The agreement between the measured and theoretical responses is excellent for both of these instruments configurations.
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Tien, Hung Nguyen, Phuong Nguyen-Hong, Minh Nguyen-Le, Wen Kuo-Liang, and Nguyen Tran-An. "Investigation of microtremor motion variation by Nakamura’S H/V spectral ratio method." Tạp chí Khoa học và Công nghệ biển 17, no. 4B (December 15, 2017): 68–74. http://dx.doi.org/10.15625/1859-3097/17/4b/12994.
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In this study, the variation of microtremor motion is investigated using observation data in Hanoi and Vung Tau cities. The results of observation conducted by times and by seismometers are processed using the Nakamura's H/V spectral ratio method and compared. For investigation, the observations have been conducted with frequency of 27 observations per hour, 22 observations per month, 4 simultaneous observations using both Servo and K2 seismometers, and 12 simultaneous observation using 7 Servo seismometers. The results of data analysis show that the values of dominant frequency and shapes of the H/V spectral ratio obtained are similar in the frequency range from 0.4 Hz to 5 Hz, especially on the dominant frequency domain. The results confirm that the microtremor variation observations can be carried out with one observation time or by multiple seismometers.
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Qi, Wenjie, Chao Xu, Bowen Liu, Xu She, Tian Liang, Deyong Chen, Junbo Wang, and Jian Chen. "MEMS-Based Electrochemical Seismometer with a Sensing Unit Integrating Four Electrodes." Micromachines 12, no. 6 (June 15, 2021): 699. http://dx.doi.org/10.3390/mi12060699.
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This paper presents a new process to fabricate a sensing unit of electrochemical seismometers using only one silicon–glass–silicon bonded wafer. By integrating four electrodes on one silicon–glass–silicon bonded wafer, the consistency of the developed sensing unit was greatly improved, benefiting from the high alignment accuracy. Parameter designs and simulations were carried out based on this sensing unit, which indicated that the sensitivities of the developed electrochemical seismometer decreased with the decrease in the number of flow holes in the sensing unit, and the initial stabilization time decreased gradually with the decrease in the thickness of the glass layer. Based on experimental results of four devices, the peak sensitivity was quantified as 5345.45 ± 43.78 V/(m/s) at 2 Hz, which proved high consistency of the fabricated electrochemical seismometer. In terms of the responses to random ground motions, high consistencies between the developed electrochemical seismometer and the commercial counterpart of CME6011 (R-sensors, Moscow, Russia) were found, where the developed electrochemical seismometer produced comparable noise levels to those of CME6011. These results validated the performance of the device and it may function as an effective tool for a variety of applications.
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Guo, Hu Sheng, Bin Yan, and Zhi Dong Wu. "The Design of New Low Cost Ocean Bottom Seismometers." Applied Mechanics and Materials 226-228 (November 2012): 2107–10. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.2107.
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The performance of the Ocean Bottom Seismometers (OBS) in seismic wave field measurement is vital to seismic exploration. In order to improve the performance of OBS, we have been developed a new Ocean Bottom Seismometer based 3-component MEMS accelerometer sensors. In order to sample seismic data synchronously, we have been designed multichannel A/D unit under the control of MSP430.We also are involved in a handle and sophisticated equipment allows to storage sampling data in the SD card module. The system based MEMS sensor are compared with conventional analog moving coil geophones, the result shows that the new measurement system with the advantage of high dynamic range, low noise and anti-jamming that suit for the high resolution seismicity information. The paper show that the new digital OBS using MEMS accelerometer will replace the tradition OBS in oil exploration, scientific research and seabed surveys.
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Jiang, Jinzhong, Runhai Yang, Bin Wang, Ya Xiang, Weidong Pang, Jun Yang, Xiaobin Li, and Beng Ye. "Assessing Short‐Term Clock Errors and Drifts of Temporary Seismic Networks Using the Active Airgun Source in Binchuan, Yunnan." Seismological Research Letters 90, no. 6 (October 2, 2019): 2165–74. http://dx.doi.org/10.1785/0220190098.
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ABSTRACT We conducted a short‐term airgun experiment at the Binchuan Fixed Airgun Signal Transmission Station from 14 to 20 February 2017, and two different types of seismometers (Güralp CMG‐40T and QS05A) recorded 62 airgun shots triggered under the same conditions. However, we observed significant clock errors and drifts in seismic data recorded by four QS05A seismometers. To assess the short‐term clock errors and drifts for seismometers, we propose a new method that measures the P‐wave arrival‐time differences between airgun signals recorded at a station pair, using the matched filter method. We find ∼1.0 s absolute clock errors for two Güralp CMG‐40T stations (CKT2 and 53261) and one QS05A station (STA05), as well as ∼0.5 s timing leaps for four QS05A stations (STA19, STA21, STA31, and STA33) during the experiment. Furthermore, all the QS05A seismometers exhibit clock drifts with similar linear trends. Additionally, we use teleseismic waveforms to verify the absolute clock errors for stations CKT2, 53261, and STA05. After double‐checking several possible factors, we determine the hardware failure or malfunctioning that may cause clock errors for the two types of seismometers.
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Riedesel, Mark A., John A. Orcutt, and Robert D. Moore. "Limits of sensitivity of inertial seismometers with velocity transducers and electronic amplifiers." Bulletin of the Seismological Society of America 80, no. 6A (December 1, 1990): 1725–52. http://dx.doi.org/10.1785/bssa08006a1725.
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Abstract Portable instruments such as ocean bottom seismographs and the PASSCAL recorders often use rugged, portable geophones. The desire to use such sensors for relatively low-frequency work has raised questions about the limits of their sensitivity. The lower and upper frequency limits of performance of seismic sensors are determined by the sensor's mass, period, and Q, and by the amplifiers used with those sensors. We have tested Mark Products 1 Hz, 2 Hz, and 4.5 Hz velocity transducers against Streckeisen seismometers in order to examine the limits of their performance in measuring ground noise, particularly at low frequencies. Among the velocity transducers, only the 1 Hz Mark Products L-4 sensor provided good resolution of the 6-sec microseism peak. For this sensor, the lower limits of sensitivity was at approximately 0.06 Hz, although this depends on the amplifier used and the noise level at a given site. The amplifiers examined included conventional, low power, and commutating auto-zero operational amplifiers. It was found that the noise levels of the amplifiers intersected the ground noise level at frequencies ranging between 0.06 and 0.2 sec, depending on the amplifier and the exact circuit design. Measurements indicated that by modeling the amplifier noise for a given circuit correctly, the performance of an amplifier can be predicted with a high degree of accuracy, obviating the need for actual circuit construction to determine performance in the field. Given the very steep slope of the ground noise spectrum between 0.05 and 0.1 Hz and the rapid fall off in a seismometer's output below its resonant frequency, it would require a lowering of amplifier noise by more than an order of magnitude to be able to resolve ground noise at frequencies lower than 0.05 Hz using relatively small geophones such as the L-4. To resolve ground noise at lower frequencies, it is necessary to use a seismometer with a displacement transducer to sense the mass position, such as Guralp or Streckeisen sensors.
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Eltekov, A. Yu, O. A. Gerasimchuk, P. M. Utkin, and Yu A. Vinogradov. "Researches and measurements of high-sensitive seismometers at experimental base «Obninsk»." Russian Journal of Seismology 6, no. 2 (June 25, 2024): 52–69. http://dx.doi.org/10.35540/2686-7907.2024.2.04.
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One of the main directions of new seismometers development for seismological monitoring systems is decreasing the instrumental noise level and nonlinearity distortions of the instrumental seismic channels. In accordance with modern requirements for high-sensitive seismological stations, the instrumental noise of seismometers should be at least three times less than local seismic background noise. By theoretical estimations modern high-sensitive seismometers have high level features: instrumental noise is lower than the minimal seismic background noise, nonlinearity factor is about 0,01% and less. However, the problem of experimental estimation of these parameters in conditions of ambient seismic backgrounds remains to be under consideration. This problem is especially important during development and production of new seismometers. The article presents some results of studying and measuring the instrumental noise level and nonlinearity factor in channels of broadband and short-period seismometers carried out at the experimental base “Obninsk”. To provide a high precision of measurements, the narrow-band digital filtration and spectrum-correlation data procession technique decreasing influence of the seismic background motion on the results uncertainty were used. Due to stable temperature and insulation in the gallery of 30-meter depth, a 20-30% uncertainty for instrumental noise characteristic measuring, which is 10-30 times lower than local seismic background noise, and 0.0004% uncertainty of nonlinearity factor measuring were achieved. The seismological and environmental conditions at the experimental base “Obninsk” of the Geophysical Survey of RAS provide necessary abilities for researche and measurement of instrumental noise characteristics and non-linear distortion factor of high-sensitive seismometers with satisfactory accuracy.
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Hakim, Arif Rachman, Adhi Harmoko Saputro, Supriyanto Rohadi, Mohamad Taufik Gunawan, and Ricko Kardoso. "Seismic Noise Analysis in InaTEWS Earthquake Station Network (Case Study: Flores Earthquake 7.4, 14 December 2021)." IOP Conference Series: Earth and Environmental Science 1047, no. 1 (July 1, 2022): 012019. http://dx.doi.org/10.1088/1755-1315/1047/1/012019.
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Abstract Meteorological, Climatology and Geophysics Agency (BMKG) is the agency responsible for providing information on earthquake parameters in Indonesia. BMKG has installed 411 seismometers network spread across Indonesia, this network is known as the Indonesia Tsunami Early Warning System (InaTEWS) network. The dense distribution of the seismometer is expected to be able to provide accurate earthquake parameter results. However, the accuracy of earthquake parameters does not only depend on many stations but also on the quality of the data recorded by the seismometer. In this study, an analysis of 15 data quality was carried out at the nearest station that recorded the Flores earthquake on December 14, 2021. Analysis of data quality using the power spectral density (PSD) and probability density functions (PDFs) methods, where good data quality can be seen in the spectrum of the seismograph recordings that are between the Peterson’s new high noise model (NHNM) and new low noise model (NLNM).
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NISIHMURA, Keiichi, Wataru MORII, and Masakuni HASHIDA. "Some Results of Seismic Observation Using a Linear Strain Seismometer in Combination with Pendulum Seismometers." Zisin (Journal of the Seismological Society of Japan. 2nd ser.) 38, no. 3 (1985): 435–46. http://dx.doi.org/10.4294/zisin1948.38.3_435.
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Wysession, Michael E. "How well do we utilize global seismicity?" Bulletin of the Seismological Society of America 86, no. 5 (October 1, 1996): 1207–19. http://dx.doi.org/10.1785/bssa0860051207.
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Abstract This article describes a method for quantifying the ability to record teleseismic phases at particular epicentral distance ranges, given the geographical history of global seismicity. With the use of geographical sampling maps, we identify the regions of the Earth that are best suited to record the greatest numbers of earthquakes at particular distances. Since seismic studies of the Earth's interior use teleseismic phases that have unique ranges, this information can be useful in the planning of future permanent and temporary deployments of seismometers. Deployment of ocean-bottom seismometers would be required for recording large numbers of earthquakes in the 40° to 80° range, corresponding to phases like ScS and PcP, and in the 140° to 170° range, important for investigations of the PKP branches. An examination of existing analog and digital networks shows that they do either better or worse than a hypothetical grid of evenly spaced seismometers, depending upon the distance range examined. The use of temporary deployments of seismometers, perhaps even in the oceans, may be the best way to significantly sample poorly examined regions of the Earth's interior.
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Koketsu, K., M. Takahashi, and S. Sakai. "Accidental Explosions Observed by Seismometers." Seismological Research Letters 73, no. 2 (March 1, 2002): 136–43. http://dx.doi.org/10.1785/gssrl.73.2.136.
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TSUKUDA, Tameshige, and Megumi MIZOUE. "Avalanche Tremors Detected by Seismometers." Zisin (Journal of the Seismological Society of Japan. 2nd ser.) 41, no. 1 (1988): 47–57. http://dx.doi.org/10.4294/zisin1948.41.1_47.
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Kabychenko, N. V., A. N. Besedina, S. G. Volosov, S. A. Korolev, and G. G. Kocharyan. "Short-Period Seismometers in Seismology." Seismic Instruments 54, no. 1 (January 2018): 28–42. http://dx.doi.org/10.3103/s074792391801005x.
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Fremd, V. M. "Symmetric Triaxial Rotational Piezoelectric Seismometers." Seismic Instruments 56, no. 4 (July 2020): 373–79. http://dx.doi.org/10.3103/s0747923920040039.
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Duennebier, Fred K., and George H. Sutton. "Why bury ocean bottom seismometers?" Geochemistry, Geophysics, Geosystems 8, no. 2 (February 2007): n/a. http://dx.doi.org/10.1029/2006gc001428.
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Butler, R. "Roum for seismometers in Lebanon." Astronomy & Geophysics 38, no. 3 (June 1, 1997): 4. http://dx.doi.org/10.1093/astrog/38.3.4.
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Hou, Yue, Rui Jiao, and Hongyu Yu. "MEMS based geophones and seismometers." Sensors and Actuators A: Physical 318 (February 2021): 112498. http://dx.doi.org/10.1016/j.sna.2020.112498.
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Liu, Hsi-Ping, Richard E. Warrick, Robert E. Westerlund, and Jon B. Fletcher. "A three-component borehole seismometer for earthquake seismology." Bulletin of the Seismological Society of America 81, no. 6 (December 1, 1991): 2458–85. http://dx.doi.org/10.1785/bssa0810062458.
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Abstract We have developed a three-component borehole seismometer, using 2-Hz electromagnetic moving-coil geophones as sensing elements. The main achievement of our new borehole package is a compact internal device for leveling horizontal geophones. Horizontal moving-coil geophones with a period longer than 0.5 sec need to be leveled to better than 1.5° to avoid nonlinear response and asymmetric clipping. In boreholes, where the axis of the package may well deviate from the vertical by more than 1.5°, a special device is required for leveling the horizontal geophones. A gimbal stage was adapted from the design of ocean-bottom seismometers for leveling the two orthogonally oriented horizontal geophones: the geophones can be leveled to better than 0.1° from an initial tilt of 10.5°. The external package is 14 cm in diameter and approximately 40 cm long. The gimbal stage uses free-flex flexural pivots and, during the leveling operation, suspends a brass pendulum that houses the horizontal sensors. In comparison with borehole seismometers that use electronic-feedback principles, the disadvantages of our system are a lack of response at long periods and, because of coil contacting stops, its inability to record strong motions. Nonetheless, it has an inherently low noise level, consumes no power, is simple to build, and is inexpensive; it is therefore suitable for rapid deployment for aftershock studies and for low-noise operation at remote sites. Such seismometers, using Mark Products L-22D 2-Hz geophones, have been installed at several sites in California: at the bottom of adjacent boreholes ∼ 150 and ∼ 300 m deep, in granite at station KNW near Keenwild and at Piñon Flat of the Anza digital seismic array, and at the bottom of an 88-m-deep borehole in hydrothermally altered serpentine in the Marina District of San Francisco. The effects of cable impedance on the geophone output have been analyzed and found to be negligible for a cable length of 335 m consisting of four pairs of shielded #20 gauge wires. Azimuthal orientation of horizontal geophones can be determined using first P-arrival particle motion generated by regional earthquakes. Earthquake data recorded by these borehole seismometers have been employed by several investigators for studies on the effects of near-surface weathered rocks on the corner frequencies of earthquake spectra near Anza, California, on the seismic-shear-wave-polarization characteristics of seismograms recorded in the southern California batholith at 300 m depth, and on site-resonance amplification caused by sedimentary deposits overlying bedrock in the Marina District of San Francisco.