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1
Dowrick, David J., Graham T. Hancox, Nick D. Perrin y Grant D. Dellow. "The Modified Mercalli intensity scale". Bulletin of the New Zealand Society for Earthquake Engineering 41, n.º 3 (30 de septiembre de 2008): 193–205. http://dx.doi.org/10.5459/bnzsee.41.3.193-205.
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Recent studies of the effects and Modified Mercalli (MM) intensities of New Zealand earthquakes have established criteria that will improve the reliability of intensities assigned using a number of effects, particularly the incidence of chimney damage and a wide range of environmental phenomena. The proportions of brittle chimneys which were damaged at intensities MM5–MM10 have been counted from the very detailed database of the 1968 Mw 7.2 Inangahua earthquake, and are shown to relate well to the proportions of chimneys which fell in 10 other earthquakes. Criteria based on environmental effects at intensities MM5-MM10 have been extended based on detailed studies of 22 earthquakes. These criteria have been adopted in an international intensity scale for environmental effects.
It was also found that the stopping of clocks should be a criterion for MM3, not MM5, and similarly the disturbance of liquids should be used at the threshold intensity of MM3 rather than MM4, as in the present MM intensity scale.
With the probable saturation of intensity at MM10, the criteria for MM12 have been omitted.
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Dowrick, D. J. "The Modified Mercalli earthquake intensity scale". Bulletin of the New Zealand Society for Earthquake Engineering 29, n.º 2 (30 de junio de 1996): 92–106. http://dx.doi.org/10.5459/bnzsee.29.2.92-106.
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The 1992 New Zealand version of the Modified Mercalli (MM) intensity scale, was the result of a major multi-disciplinary review, and comments were invited. This paper results from considerable use of the 1992 scale in recent studies of twenty two New Zealand earthquakes including two of magnitude Ms7.8, and insights into the scale gained from studies of the well-documented Mw6.6 1987 Edgecumbe earthquake. Improvements to the 1992 New Zealand MM intensity scale are offered, including criteria for chimney damage at MM6 to MM8, and also criteria for MM10 to MM12 based on a simple matrix procedure of logical extrapolation from lower intensities, and the use of new construction categories. Discussions of the influence of ground conditions at high intensities, and on definitions of the key terms "partial collapse", "collapse" and "destroyed", are included.
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Onur, Tuna, Carlos E. Ventura y W. D. Liam Finn. "A comparison of two regional seismic damage estimation methodologies". Canadian Journal of Civil Engineering 33, n.º 11 (1 de noviembre de 2006): 1401–9. http://dx.doi.org/10.1139/l06-084.
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This paper presents a comparison of the two main regional damage estimation methodologies currently in use, namely the modified Mercalli intensity (MMI) based approach and the spectral parameter based approach. In the first methodology, expected damage is related to ground shaking intensity in terms of MMI through damage probability matrices. In the second methodology, the ground motion intensity is described in terms of spectral acceleration (SA), and building response in terms of spectral displacement (SD). Both methodologies were applied to buildings in Vancouver of three different construction types: single-family wood-frame houses, low-rise unreinforced masonry buildings, and high-rise concrete frame structures with concrete shear walls. The two methodologies predict damage that lies in the same general damage categories of light and moderate, which are defined by fairly broad ranges in mean damage factors. The specific mean damage factors predicted by the two methods for a given location are significantly different, however. The significant differences in mean damage factors imply significant differences in damage costs and hence in seismic risk.Key words: earthquake, damage, seismic risk, vulnerability, modified Mercalli intensity (MMI), spectral response, displacement, acceleration.
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Boatwright, John, Howard Bundock y Linda C. Seekins. "Using Modified Mercalli Intensities to Estimate Acceleration Response Spectra for the 1906 San Francisco Earthquake". Earthquake Spectra 22, n.º 2_suppl (abril de 2006): 279–95. http://dx.doi.org/10.1193/1.2186348.
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We derive and test relations between the Modified Mercalli Intensity (MMI) and the pseudo-acceleration response spectra at 1.0 and 0.3 s— SA(1.0 s) and SA(0.3 s)—in order to map response spectral ordinates for the 1906 San Francisco earthquake. Recent analyses of intensity have shown that MMI ≥ 6 correlates both with peak ground velocity and with response spectra for periods from 0.5 to 3.0 s. We use these recent results to derive a linear relation between MMI and log SA(1.0 s), and we refine this relation by comparing the SA(1.0 s) estimated from Boatwright and Bundock's (2005) MMI map for the 1906 earthquake to the SA(1.0 s) calculated from recordings of the 1989 Loma Prieta earthquake. South of San Jose, the intensity distributions for the 1906 and 1989 earthquakes are remarkably similar, despite the difference in magnitude and rupture extent between the two events. We use recent strong motion regressions to derive a relation between SA(1.0 s) and SA(0.3 s) for a M7.8 strike-slip earthquake that depends on soil type, acceleration level, and source distance. We test this relation by comparing SA(0.3 s) estimated for the 1906 earthquake to SA(0.3 s) calculated from recordings of both the 1989 Loma Prieta and 1994 Northridge earthquakes, as functions of distance from the fault.
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Ebel, John E. y David J. Wald. "Bayesian Estimations of Peak Ground Acceleration and 5% Damped Spectral Acceleration from Modified Mercalli Intensity Data". Earthquake Spectra 19, n.º 3 (agosto de 2003): 511–29. http://dx.doi.org/10.1193/1.1596549.
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We describe a new probabilistic method that uses observations of modified Mercalli intensity (MMI) from past earthquakes to make quantitative estimates of ground shaking parameters (i.e., peak ground acceleration, peak ground velocity, 5% damped spectral acceleration values, etc.). The method uses a Bayesian approach to make quantitative estimates of the probabilities of different levels of ground motions from intensity data given an earthquake of known location and magnitude. The method utilizes probability distributions from an intensity/ground motion data set along with a ground motion attenuation relation to estimate the ground motion from intensity. The ground motions with the highest probabilities are the ones most likely experienced at the site of the MMI observation. We test the method using MMI/ground motion data from California and published ground motion attenuation relations to estimate the ground motions for several earthquakes: 1999 Hector Mine, California (M7.1); 1988 Saguenay, Quebec (M5.9); and 1982 Gaza, New Hampshire (M4.4). In an example where the method is applied to a historic earthquake, we estimate that the peak ground accelerations associated with the 1727 (M∼5.2) earthquake at Newbury, Massachusetts, ranged from 0.23 g at Newbury to 0.06 g at Boston.
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Dowrick, D. J. y W. J. Cousins. "Historical incidence of Modified Mercalli intensity in New Zealand and comparisons with hazard models". Bulletin of the New Zealand Society for Earthquake Engineering 36, n.º 1 (31 de marzo de 2003): 1–24. http://dx.doi.org/10.5459/bnzsee.36.1.1-24.
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The historical incidence of Modified Mercalli intensity produced by earthquakes of magnitude Mw ≥ 5.25 and depth ≤ 100 km has been determined for 47 locations in New Zealand for the period 1840-1997 inclusive. Maps for the return periods of intensities MM4 - MM7 were prepared. The effects of the highly attenuating Taupo Volcanic Zone (TVZ) were shown to be important for hazard both in the zone and in areas to the north-west of it. The rate of occurrence of the higher intensities was found to be about 2.5 times greater in the first century of the study period than in the last 50 years. The historical seismic hazard rates for intensities MM5 and MM6 averaged across the country were found to be approximately half those of the now obsolete Smith & Berryman seismic hazard model, and 70% of those of the more recent Stirling et al model.
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Shabestari, Khosrow T. y Fumio Yamazaki. "A Proposal of Instrumental Seismic Intensity Scale Compatible with MMI Evaluated from Three-Component Acceleration Records". Earthquake Spectra 17, n.º 4 (noviembre de 2001): 711–23. http://dx.doi.org/10.1193/1.1425814.
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Seismic intensity provides useful information on the regional distribution of earthquake effects and has been used to assess seismic hazards and damages. The concept of intensity has been considered as a method to classify severity of the ground motion on the basis of observed effects in the stricken area. In 1996, the Japan Meteorological Agency (JMA) developed a new seismic intensity measurement scale using three-component strong ground motion records in order to provide a measure of the strength of the seismic motion, which is compatible with the existing JMA intensity scale. By applying a band-pass filter to the frequency domain and a vectoral composition of the three components in the time domain, the JMA seismic intensity scale (IJMA) can be calculated without subjective judgement. In this study, we apply the IJMA method to the acceleration records of three recent significant earthquakes in California. For a Modified Mercalli Intensity (MMI) between IV and VIII, a new relation between MMI and log a0, obtained in the process of calculating the new IJMA, is given by the equation MMI=3.93 log a0−1.17. We propose this relation as a new instrumental seismic intensity (IMM) compatible with the California region MMI.
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Iswahyudi, Iswahyudi y Emmy Darmawati. "Introduksi Pengukuran Getaran Berbasis Android Saat Transportasi Jambu Air Camplong". Jurnal BETA (Biosistem dan Teknik Pertanian) 9, n.º 1 (30 de abril de 2021): 125. http://dx.doi.org/10.24843/jbeta.2021.v09.i01.p13.
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ABSTRAK
Jambu air camplong (Syzygium aqueum (Burm.f.) Alston) merupakan buah unggulan Madura yang bernilai ekonomis, dibutuhkan dalam bentuk segar namun mudah rusak. Kesegaran produk akan terjaga jika dilakukan pengemasan dan transportasi yang baik. Tujuan penelitian ini adalah melakukan transportasi sesungguhnya jambu air camplong dan memperkenalkan cara baru mengukur getaran berbasis Android. Skala pengukuran getaran di lapangan adalah MMI (Modified Mercalli Intensity Scale). Hasil penelitian menunjukkan, pengukuran getaran menggunakan Android menggambarkan langsung pengaruh getaran saat transportasi terhadap kemasan, getaran yang ditimbulkan sebesar 7-8 MMI dan gaya yang ditimbulkan sebesar 0,8 – 1,2 kgf sehingga tidak berpengaruh terhadap kemasan yang digunakan. Persentase kerusakan mekanis jambu air camplong pasca transportasi sebesar 20.87 % pada kemasan petani dan 7.70 % pada kemasan RSC.
ABSTRACT
The camplong water apple (Syzygium aqueum (Burm.f.) Alston) is a superior fruit of Madura which has economic value. It is needed in fresh form but is easily damaged. Product freshness will be maintained if proper packaging and transportation are carried out. The purpose of this research was to carry out the actual transportation of guava water and introduced a new way of measuring vibrations based on Android. The scale for measuring vibrations in the field was based on MMI (Modified Mercalli Intensity Scale). The results showed that the measurement of vibration using Android directly illustrated the effect of vibration during transportation on the packaging, the vibration generated was 7-8 MMI and the resulting force was 0.8 - 1.2 kgf so that it did not affect the packaging used. The percentage of mechanical damage to guava air camplong after transportation was 20.87% on farmer packaging and 7.70% on RSC packaging.
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Goded, Tatiana, Matt Gerstenberger, Mark Stirling, Jim Cousins y Silvia Canessa. "High-Intensity Assignments for the 22 February 2011 Mw 6.2 Christchurch, Canterbury, New Zealand, Earthquake: A Contribution toward Understanding the Severe Damage Caused by This Event". Seismological Research Letters 90, n.º 4 (17 de abril de 2019): 1468–82. http://dx.doi.org/10.1785/0220180385.
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ABSTRACT This article presents modified Mercalli intensity (MMI) data for the 22 February 2011 Mw 6.2 Christchurch, New Zealand, earthquake. These data include intensity levels above MMI 8 that have not been assigned previously. Two sources of data have been used in this research: GeoNet’s “Felt Classic” online questionnaires and felt reports gathered during a field study in Christchurch in February 2013. Taken together, these sets of data provided 331 valid (i.e., with all the needed information) felt reports in areas of MMI 8 or above, with 299 (90%) of the reports used to assign MMI levels above 8. This article presents a more detailed picture of the geographical damage distribution of this earthquake than has previously been available. The data differentiate damage in the center of Christchurch, with 8 communities assigned a community MMI (CMMI) of 9, 11 communities a CMMI of 10, and 8 communities a CMMI of 11, which is the maximum possible intensity in the New Zealand MMI scale, and a level of intensity not previously reported in New Zealand (Dowrick et al., 2008). The geographical damage distribution for Christchurch has been updated for intensities below MMI 8. This was done using a recently developed method that groups intensity data and allows intensities to be aggregated for a community and a single value assigned. Comparisons between MMI and peak ground velocity using the CMMI data and two ground-motion intensity correlation equations (GMICEs) indicate an underestimation of MMI when using the GMICEs and the need to review New Zealand’s GMICE.
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Bodle, Thomas. "Microzoning the Likelihood of Strong Spectral Amplification of Earthquake Motions Using MMI Surveys and Surface Geology". Earthquake Spectra 8, n.º 4 (noviembre de 1992): 501–27. http://dx.doi.org/10.1193/1.1585693.
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A statistically based microzonation tool for delineating zones within a region most susceptible to strong spectral amplification of earthquake accelerations in the 2 to 4 Hertz range is introduced using detailed Modified Mercalli Intensity (MMI) surveys and surface geology. A rationale for the research method is discussed using four arguments: the Fourier spectral analysis of earthquake ground motions and the spectral response method; an empirical versus a theoretical justification, low cost, and a consideration for previous research into the topic specific to the area of the case study chosen.
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Smith, Ellen M. y Walter D. Mooney. "A Seismic Intensity Survey of the 16 April 2016 Mw 7.8 Pedernales, Ecuador, Earthquake: A Comparison with Strong-Motion Data and Teleseismic Backprojection". Seismological Research Letters 92, n.º 4 (31 de marzo de 2021): 2156–71. http://dx.doi.org/10.1785/0220200290.
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Abstract We conducted a seismic intensity survey in Ecuador, following the 16 April 2016 Mw 7.8 Pedernales earthquake, to document the level of damage caused by the earthquake. Our modified Mercalli intensities (MMIs) reach a maximum value of VIII along the coast, where single, two, and multistory masonry and concrete designed buildings partially or completely collapsed. The contours of our MMI maps are similar in shape to the contour maps of peak ground acceleration (PGA) and peak ground velocity (PGV). A comparison of our seismic intensities with the recorded PGA and PGV values reveals that our MMI values are lower than predicted by ground-motion intensity conversion equations that are based on shallow crustal earthquakes. The image of the earthquake rupture obtained using teleseismic backprojection at 0.5–2.0 Hz is coincident with the region of maximum MMI, PGA, and PGV values, Thus, rapid calculation of backprojection may be a useful tool for guiding the deployment of emergency response teams following large earthquakes. The most severe damage observed was, primarily, due to a combination of poorly constructed buildings and site conditions.
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Sana, Hamid, Petra Štěpančíková, Annika Szameitat y Jakub Stemberk. "Macroseismic Intensity Re-Evaluation of the 11 June 1895 Mid-Silesia, Poland, Earthquake". Seismological Research Letters 92, n.º 2A (13 de enero de 2021): 1159–67. http://dx.doi.org/10.1785/0220200359.
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Abstract Earthquakes in slowly deforming intraplate regions like Poland are not as frequent or of high intensity as at the plate boundaries. However, few low-to-moderate intensity earthquakes have been reported to have shaken different regions of Poland in the late nineteenth and early twentieth centuries. We present an intensity re-evaluation of one of these earthquakes—the 11 June 1895 Mid-Silesia, southwestern Poland earthquake. Damage reports were collected from 563 towns and villages of the Silesia region soon after the earthquake. However, these reports and the names of the places are in German. The damage reports were translated from German to English and the names of the places to present names in Polish. The intensity re-evaluation was carried out using the modified Mercalli intensity (MMI) scale. The highest intensity on the MMI scale is evaluated to be VII in two important towns of Strzelin and Ziębice. The reports mention damage to the estate officer’s house by the 11 June 1895 Mid-Silesia earthquake. In this study, the location of the estate officer’s house was determined, and suspected earthquake damage to the building was demarcated.
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Atkinson, Gail M. "The Intensity of Ground Motions from Induced Earthquakes with Implications for Damage Potential". Bulletin of the Seismological Society of America 110, n.º 5 (10 de marzo de 2020): 2366–79. http://dx.doi.org/10.1785/0120190166.
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ABSTRACT The damage potential of induced earthquakes is compared to that of natural tectonic events, considering recent instrumental data and felt records from events of M 3.5–5.8 (in which M is the moment magnitude). Ground motions are mutually consistent at close distances (<30 km) for natural earthquakes in California, induced earthquakes in Oklahoma, and induced earthquakes in western Canada, despite differences in the dominant processes that trigger the events. Recorded peak ground motions may exceed the damage threshold for induced events of M∼4.0 within ∼5 km of the hypocenter; events of M≥4.5 are inferred to have significant damage potential within 5 km and may be damaging to greater distances. Felt and damage effects in Oklahoma, as reported on the U.S. Geological Survey’s online “Did You Feel It?” system, show that the damage threshold (modified Mercalli intensity [MMI] = 6) is commonly exceeded for events of M∼4.5 at close distances (<10 km) and that significant damage effects (MMI=7) are observed for M>4.8 events within 10 km.
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Stirling, Mark, Matthew Gerstenberger, Nicola Litchfield, Graeme McVerry, Warwick Smith, Jarg Pettinga y Philip Barnes. "Seismic hazard of the Canterbury region, New Zealand". Bulletin of the New Zealand Society for Earthquake Engineering 41, n.º 2 (30 de junio de 2008): 51–67. http://dx.doi.org/10.5459/bnzsee.41.2.51-67.
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We present a new probabilistic seismic hazard model for the Canterbury region, the model superseding the earlier model of Stirling et al. (1999, 2001). The updated model incorporates new onshore and offshore fault data, new seismicity data, new methods for the earthquake source parameterisation of both datasets, and new methods for estimation of the expected levels of Modified Mercalli Intensity (MMI) across the region. While the overall regional pattern of estimated hazard has not changed since the earlier seismic hazard model, there have been slight reductions in hazard in some areas (western Canterbury Plains and eastern Southern Alps), coupled with significant increases in hazard in one area (immediately northeast of Kaikoura). The changes to estimated acceleration for the new versus older model serve to show the extent that major changes to a multidisciplinary source model may impact the final estimates of hazard, while the new MMI estimates show the added impact of a new methodology for calculating MMI hazard.
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Saunders, Jessie K., Brad T. Aagaard, Annemarie S. Baltay y Sarah E. Minson. "Optimizing Earthquake Early Warning Alert Distance Strategies Using the July 2019 Mw 6.4 and Mw 7.1 Ridgecrest, California, Earthquakes". Bulletin of the Seismological Society of America 110, n.º 4 (9 de junio de 2020): 1872–86. http://dx.doi.org/10.1785/0120200022.
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ABSTRACT The ShakeAlert earthquake early warning system aims to alert people who experience modified Mercalli intensity (MMI) IV+ shaking during an earthquake using source estimates (magnitude and location) to estimate median-expected peak ground motions with distance, then using these ground motions to determine median-expected MMI and thus the extent of MMI IV shaking. Because median ground motions are used, even if magnitude and location are correct, there will be people outside the alert region who experience MMI IV shaking but do not receive an alert (missed alerts). We use 91,000 “Did You Feel It?” survey responses to the July 2019 Mw 6.4 and Mw 7.1 Ridgecrest, California, earthquakes to determine which ground-motion to intensity conversion equation (GMICE) best fits median MMI with distance. We then explore how incorporating uncertainty from the ground-motion prediction equation and the GMICE in the alert distance calculation can produce more accurate MMI IV alert regions for a desired alerting strategy (e.g., aiming to alert 95% of people who experience MMI IV+ shaking), assuming accurate source characterization. Without incorporating ground-motion uncertainties, we find MMI IV alert regions using median-expected ground motions alert fewer than 20% of the population that experiences MMI IV+ shaking. In contrast, we find >94% of the people who experience MMI IV+ shaking can be included in the MMI IV alert region when two standard deviations of ground-motion uncertainty are included in the alert distance computation. The optimal alerting strategy depends on the false alert tolerance of the community due to the trade-off between minimizing missed and false alerts. This is especially the case for situations like the Mw 6.4 earthquake when alerting 95% of the 5 million people who experience MMI IV+ also results in alerting 14 million people who experience shaking below this level and do not need to take protective action.
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Rosset, Philippe, Allison L. Bent y Luc E. Chouinard. "Correlating DYFI Data With Seismic Microzonation in the Region of Montreal". Earth Science Research 9, n.º 2 (31 de julio de 2020): 85. http://dx.doi.org/10.5539/esr.v9n2p85.
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The Western Quebec seismic zone has moderate seismic activity with few historical damaging earthquakes. Nevertheless, recent risk analyses have shown that the combination of a high level of urbanization with soft soil deposits in the metropolitan area of Montreal could lead to significant damage and economic losses. Over the two decades, several projects have been completed to develop a seismic microzonation to identify zones where seismic waves could be amplified. During the same period, Natural Resources Canada developed an internet application to collect reports from the population after an earthquake and to convert them to the Modified Mercalli Intensity scale (MMI). This paper presents a first comparison of the MMI data compiled after eight recent earthquakes felt in Montreal area with the existing zonation in terms of soil classes. It shows that the MMI from individual reports increases when the observer is located in a soft soil zone. Statistics on average MMI over a regular grid confirms this trend. The numerous reports collected through the internet application, and future applications based on data collected from social media, could become a very useful source of information to complement seismic field measurements when developing and validating seismic microzonation maps.
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Campbell, Kenneth W. y Yousef Bozorgnia. "Cumulative Absolute Velocity (CAV) and Seismic Intensity Based on the PEER-NGA Database". Earthquake Spectra 28, n.º 2 (mayo de 2012): 457–85. http://dx.doi.org/10.1193/1.4000012.
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Cumulative absolute velocity (CAV) has been proposed as an instrumental index to quantify the potential earthquake damage to structures. We explore this idea further by developing a relationship between the standardized version of CAV and the Japan Meteorological Agency (JMA) and modified Mercalli (MMI) instrumental seismic intensities in order to correlate standardized CAV with the qualitative descriptions of damage in the corresponding macroseismic intensity scales. Such an analysis statistically identifies the threshold values of standardized CAV associated with the onset of damage to buildings of good design and construction inherent in these scales. Based on these results, we suggest that CAV might be used to rapidly assess the potential damage to a general class of conventional structures after an earthquake. However, other ground motion or damage-related parameters might be better suited to quantifying the potential damage to structures of a specific type and size.
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Tian, Xiufeng, Zengping Wen, Weidong Zhang y Jie Yuan. "New Ground Motion to Intensity Conversion Equations for China". Shock and Vibration 2021 (29 de julio de 2021): 1–21. http://dx.doi.org/10.1155/2021/5530862.
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In this study, we use the strong motion records and seismic intensity data from 11 moderate-to-strong earthquakes in the mainland of China since 2008 to develop new conversion equations between seismic intensity and peak ground motion parameters. Based on the analysis of the distribution of the dataset, the reversible conversion relationships between modified Mercalli intensity (MMI) and peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo-spectral acceleration (PSA) at natural vibration periods of 0.3 s, 1.0 s, 2.0 s, and 3.0 s are obtained by using the orthogonal regression. The influence of moment magnitude, hypocentral distance, and hypocentral depth on the residuals of conversion equations is also explored. To account for and eliminate the trends in the residuals, we introduce a magnitude-distance-depth correction term and obtain the improved relationships. Furthermore, we compare the results of this study with previously published works and analyze the regional dependence of conversion equations. To quantify the regional variations, a regional correction factor for China, suitable for adjustment of global relationships, has also been estimated.
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Thywissen, Katharina y John Boatwright. "Using safety inspection data to estimate shaking intensity for the 1994 Northridge earthquake". Bulletin of the Seismological Society of America 88, n.º 5 (1 de octubre de 1998): 1243–53. http://dx.doi.org/10.1785/bssa0880051243.
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Abstract We map the shaking intensity suffered in Los Angeles County during the 17 January 1994, Northridge earthquake using municipal safety inspection data. The intensity is estimated from the number of buildings given red, yellow, or green tags, aggregated by census tract. Census tracts contain from 200 to 4000 residential buildings and have an average area of 6 km2 but are as small as 2 and 1 km2 in the most densely populated areas of the San Fernando Valley and downtown Los Angeles, respectively. In comparison, the zip code areas on which standard MMI intensity estimates are based are six times larger, on average, than the census tracts. We group the buildings by age (before and after 1940 and 1976), by number of housing units (one, two to four, and five or more), and by construction type, and we normalize the tags by the total number of similar buildings in each census tract. We analyze the seven most abundant building categories. The fragilities (the fraction of buildings in each category tagged within each intensity level) for these seven building categories are adjusted so that the intensity estimates agree. We calibrate the shaking intensity to correspond with the modified Mercalli intensities (MMI) estimated and compiled by Dewey et al. (1995); the shapes of the resulting isoseismals are similar, although we underestimate the extent of the MMI = 6 and 7 areas. The fragility varies significantly between different building categories (by factors of 10 to 20) and building ages (by factors of 2 to 6). The post-1940 wood-frame multi-family (≧5 units) dwellings make up the most fragile building category, and the post-1940 woodframe single-family dwellings make up the most resistant building category.
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Caccavale, Mauro, Marco Sacchi, Efisio Spiga y Sabina Porfido. "The 1976 Guatemala Earthquake: ESI Scale and Probabilistic/Deterministic Seismic Hazard Analysis Approaches". Geosciences 9, n.º 9 (19 de septiembre de 2019): 403. http://dx.doi.org/10.3390/geosciences9090403.
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A hazard assessment of the 1976 Guatemala earthquake (M = 7.5) was conducted to achieve a better definition of the seismic hazard. The assessment was based on the environmental effects that had effectively contributed to the high destructive impact of that event. An interdisciplinary approach was adopted by integrating: (1) historical data; (2) co-seismic geological effects in terms of Environmental Seismic Intensity (ESI) scale intensity values; and (3) ground shaking data estimated by a probabilistic/deterministic approach. A detailed analysis of primary and secondary effects was conducted for a set of 24 localities, to obtain a better evaluation of seismic intensity. The new intensity values were compared with the Modified Mercalli Intensity (MMI) and Peak Ground Acceleration (PGA) distribution estimated using a probabilistic/deterministic hazard analysis approach for the target area. Our results are evidence that the probabilistic/deterministic hazard analysis procedures may result in very different indications on the PGA distributions. Moreover, PGA values often display significant discrepancy from the macroseismic intensity values calculated with the ESI scale. Therefore, the incorporation of the environmental earth effects into the probabilistic/deterministic hazard analysis appears to be mandatory in order to achieve a more accurate seismic estimation.
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Dowrick, David J. "Seismic hazard estimates for the Auckland area, and their design and construction implications". Bulletin of the New Zealand Society for Earthquake Engineering 25, n.º 3 (30 de septiembre de 1992): 211–21. http://dx.doi.org/10.5459/bnzsee.25.3.211-221.
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Revised estimates of the return periods of Modified Mercalli (MM) intensity for Auckland and Northland, arising from a revision of the attenuation of intensity in New Zealand, and latest data and views on the local seismicity and geology, represent considerable reductions in the hazard given in Smith and Berryman's seismic hazard model of New Zealand. The revised levels are MM6 and MM7 for 150 and 1200 year return periods. This implies that most structures and plant in Auckland and Northland could have much simpler and less onerous earthquake resistant design and construction than required by current codes. This simpler approach would be significantly cheaper for older so-called "earthquake risk buildings" as well as new construction.
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Ishomyl, Mukhamad. "Implementation of Wireless Sensor Network in Earthquake Warning Simulation Using SW-420 Sensor". Jurnal Jartel: Jurnal Jaringan Telekomunikasi 10, n.º 1 (12 de marzo de 2020): 38–44. http://dx.doi.org/10.33795/jartel.v10i1.184.
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The wireless sensor network is a network consisting of sensor devices that detect nearby symptoms and then send information about the obtained results. Earthquakes are natural phenomena that can come at any time. So we need a tool that works automatically to give a warning as soon as possible when a WSN-based earthquake occurs to anticipate community rescue and reduce the number of casualties. This earthquake simulation alert will provide two notifications. Visual notifications displayed on the LCD and from the web. The sound notification issued by the buzzer will be different depending on the vibration received by the SW-420 sensor. Parameter earthquake used is MMI (modified mercalli intensity) using a visual assessment, international earthquake parameters. SIG (earthquake intensity scale) which already has a PGA (Peak Ground Acceleration) unit and includes MMI in it which is made by BMKG. After an excessive vibration is detected and it exceeds a predetermined limit, the MCU node will send an analog signal to the buzzer to provide a notification that has been set. For each appear notification, it aims to direct the public as soon as possible to assembly point that has been set in each building. Each detected vibration will be stored in WEB database. The vibration results detected by the sensor are a value of 0 (low) and 1 (high). These results will be sampled and produce an output in the form of Earthquake Intensity Scale.
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Sokejima, Shigeru, Yoshimi Nakatani, Kazuomi Kario, Kazunori Kayaba, Masumi Minowa y Sadanobu Kagamimori. "Seismic Intensity and Risk of Cerebrovascular Stroke: 1995 Hanshin-Awaji Earthquake". Prehospital and Disaster Medicine 19, n.º 04 (diciembre de 2004): 297–306. http://dx.doi.org/10.1017/s1049023x00001928.
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AbstractIntroduction:No epidemiological data exist concerning the influence of an earthquake on the risk of stroke. Whether the incidence of cerebrovascular stroke increased after the 1995 Hanshin-Awaji earthquake (EQ) in Japan and whether seismic intensity affected stroke risk dose-dependently was examined.Methods:A retrospective cohort study was conducted among residents, who were living in two towns on the island of Awaji and were participants of the National Health Insurance (NHI) program. The two towns were divided into 11 districts and their respective damage and socioeconomic states were investigated. Reviewing the NHI documents issued before and after the EQ, people who had strokes (9th International Classification of Diseases, codes 430–431 or 433–434.9) were identified. Risk of stroke in relation to the seismic intensities, was assessed with the Cox proportional hazard model.Results:Among subjects aged 40 to 99 years, 45 of 8,758 (0.514%) had a stroke the year before the EQ, 72 of 8,893 (0.810%) had a stroke in the first year following the EQ, and 49 of 8,710 (0.566%) had a stroke in the second year following the EQ. In districts where the earthquake's intensity was ≤9.5 on the modified Mercalli intensity (MMI), compared with the year prior to the EQ, the relative risk (RR) of stroke was 2.4 (95% confidence interval (CI) 1.1, 5.0) in the first year following the EQ, after adjusting for age, gender, and income. In that year, compared with MMI of <8.5–9.0, RRs for 9.0–9.5 and ≥9.5 were 1.6 (CI 0.9, 2.1) and 2.0 (CI 1.1, 3.7), respectively (pfor trend 0.02). No trend for the RR was observed in the year before the EQ or in the second year following the EQ.Conclusion Stroke increased in the first year following the EQ. The increase was associated with seismic intensity in a dose-response manner. Results suggest a potential threshold for RR of >2.0 in areas near 9.5 on the MMI scale.
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Zafarani, Hamid, Hesam Vahidifard y Anooshirvan Ansari. "Prediction of Broadband Ground-Motion Time Histories: The Case of Tehran, Iran". Earthquake Spectra 29, n.º 2 (mayo de 2013): 633–60. http://dx.doi.org/10.1193/1.4000150.
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The northern Tehran fault (NTF) is potentially capable of causing large earth-quakes (Mmax ~ 7.2) in a very densely populated area of northern Tehran, Iran. Due to the lack of recorded strong motion data for earthquakes on the fault, a hybrid simulation method is used to calculate broadband (0.1–20 Hz) ground-motion time histories at bedrock level for deterministic earthquake scenarios on the NTF. Low-frequency components of motion (0.1–1.0 Hz) are calculated using a deterministic approach and the discrete wave number-finite element method in a regional one-dimensional (1-D) velocity model. High frequencies (1.0–20.0 Hz) are calculated by the stochastic finite fault method based on dynamic corner frequency. The results were validated by comparing the simulated peak values and response spectra with the empirical ground motion models available for the area and the Modified Mercalli intensity (MMI) observations from historical earthquakes of the region.
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Jones, Nicholas P., Sólveig Thorvaldsdóttir, Anqi Liu, Prakash Narayan y Thomas Warthen. "Evaluation of a Loss Estimation Procedure Based on Data from the Loma Prieta Earthquake". Earthquake Spectra 11, n.º 1 (febrero de 1995): 37–61. http://dx.doi.org/10.1193/1.1585802.
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Over the several past decades, methods have been developed to predict structural damage on a regional basis. This paper describes an effort to collect damage and loss data from the Loma Prieta Earthquake and the comparison of these data with the results calculated by an existing loss estimation model. First the intensity prediction was evaluated by comparing the model results with the Modified Mercalli Intensity (MMI) maps issued by the U.S. Geological Survey in areas affected by the Loma Prieta earthquake. Then, the study concentrated on losses of the City of Watsonville in the County of Santa Cruz. The sensitivity of the loss due to variation in some of the basic parameters, such as intensity, deductible and liquefaction potential, were studied and discussed. The damage distribution of wood-frame buildings was also investigated. Results of calculations were compared with the collected real loss data (on-site estimate and permit estimate) from the City of Watsonville. The comparison shows that while the extant model offers some insight into loss distributions, more research is clearly necessary to improve the physical underpinnings of the methodology and to provide the necessary statistical data on which these approaches are based.
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Dowrick, David J. y David A. Rhoades. "Risk of casualties in New Zealand earthquakes". Bulletin of the New Zealand Society for Earthquake Engineering 38, n.º 2 (30 de junio de 2005): 53–72. http://dx.doi.org/10.5459/bnzsee.38.2.53-72.
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This paper reports on a study of all earthquakes that have caused (or could have caused) casualties in New Zealand in the period 1840 - 2003 inclusive. The intensity which has been the effective threshold for injuries is Modified Mercalli intensity VII (MM7). In the period of interest at least 73 earthquakes of magnitude Mw ≥ 5 have caused MM7 or greater in populated areas, and of these events 16 have caused direct casualties, 297 deaths and 640 hospitalized injured. The causes of the casualties are tabulated and discussed, and the potential to reduce casualties in the future is assessed, in particular in a large earthquake on the Wellington fault. Death rates have been determined empirically as functions of four types of structure and MM intensity.
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Kohler, Monica D., Deborah E. Smith, Jennifer Andrews, Angela I. Chung, Renate Hartog, Ivan Henson, Douglas D. Given, Robert de Groot y Stephen Guiwits. "Earthquake Early Warning ShakeAlert 2.0: Public Rollout". Seismological Research Letters 91, n.º 3 (8 de abril de 2020): 1763–75. http://dx.doi.org/10.1785/0220190245.
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Abstract The ShakeAlert earthquake early warning system is designed to automatically identify and characterize the initiation and rupture evolution of large earthquakes, estimate the intensity of ground shaking that will result, and deliver alerts to people and systems that may experience shaking, prior to the occurrence of shaking at their location. It is configured to issue alerts to locations within the West Coast of the United States. In 2018, ShakeAlert 2.0 went live in a regional public test in the first phase of a general public rollout. The ShakeAlert system is now providing alerts to more than 60 institutional partners in the three states of the western United States where most of the nation’s earthquake risk is concentrated: California, Oregon, and Washington. The ShakeAlert 2.0 product for public alerting is a message containing a polygon enclosing a region predicted to experience modified Mercalli intensity (MMI) threshold levels that depend on the delivery method. Wireless Emergency Alerts are delivered for M 5+ earthquakes with expected shaking of MMI≥IV. For cell phone apps, the thresholds are M 4.5+ and MMI≥III. A polygon format alert is the easiest description for selective rebroadcasting mechanisms (e.g., cell towers) and is a requirement for some mass notification systems such as the Federal Emergency Management Agency’s Integrated Public Alert and Warning System. ShakeAlert 2.0 was tested using historic waveform data consisting of 60 M 3.5+ and 25 M 5.0+ earthquakes, in addition to other anomalous waveforms such as calibration signals. For the historic event test, the average M 5+ false alert and missed event rates for ShakeAlert 2.0 are 8% and 16%. The M 3.5+ false alert and missed event rates are 10% and 36.7%. Real-time performance metrics are also presented to assess how the system behaves in regions that are well-instrumented, sparsely instrumented, and for offshore earthquakes.
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Tang, Yuxiang, Nelson Lam, Hing-Ho Tsang y Elisa Lumantarna. "Use of Macroseismic Intensity Data to Validate a Regionally Adjustable Ground Motion Prediction Model". Geosciences 9, n.º 10 (30 de septiembre de 2019): 422. http://dx.doi.org/10.3390/geosciences9100422.
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In low-to-moderate seismicity (intraplate) regions where locally recorded strong motion data are too scare for conventional regression analysis, stochastic simulations based on seismological modelling have often been used to predict ground motions of future earthquakes. This modelling methodology has been practised in Central and Eastern North America (CENA) for decades. It is cautioned that ground motion prediction equations (GMPE) that have been developed for use in CENA might not always be suited for use in another intraplate region because of differences in the crustal structure. This paper introduces a regionally adjustable GMPE, known as the component attenuation model (CAM), by which a diversity of crustal conditions can be covered in one model. Input parameters into CAM have been configured in the same manner as a seismological model, as both types of models are based on decoupling the spectral properties of earthquake ground motions into a generic source factor and a regionally specific path factor (including anelastic and geometric attenuation factors) along with a crustal factor. Unlike seismological modelling, CAM is essentially a GMPE that can be adapted readily for use in different regions (or different areas within a region) without the need of undertaking any stochastic simulations, providing that parameters characterising the crustal structure have been identified. In addressing the challenge of validating a GMPE for use in an area where instrumental data are scarce, modified Mercalli intensity (MMI) data inferred from peak ground velocity values predicted by CAM are compared with records of MMI of past earthquake events, as reported in historical archives. South-Eastern Australia (SEA) and South-Eastern China (SEC) are the two study regions used in this article for demonstrating the viability of CAM as a ground motion prediction tool in an intraplate environment.
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Trifunac, M. D. y V. W. Lee. "A note on scaling peak acceleration, velocity and displacement of strong earthquake shaking by Modified Mercalli Intensity (MMI) and site soil and geologic conditions". Soil Dynamics and Earthquake Engineering 11, n.º 2 (enero de 1992): 101–10. http://dx.doi.org/10.1016/0267-7261(92)90048-i.
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Sritharan, S. y D. J. Dowrick. "Response of low-rise buildings to moderate ground shaking, particularly the May 1990 Weber earthquake". Bulletin of the New Zealand Society for Earthquake Engineering 27, n.º 3 (30 de septiembre de 1994): 205–21. http://dx.doi.org/10.5459/bnzsee.27.3.205-221.
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In the Weber earthquake of 13 May 1990 the stronger component of the ground motions recorded in Dannevirke was similar in strength to the El Centro S00E record from the 1940 Imperial Valley earthquake which underlies the New Zealand loadings code, The Modified Mercalli intensity in Dannevirke however was only about MM7 1⁄2, whereas the intensity corresponding to the 1984 earthquake code is about MM8 1⁄2 for the Dannevirke area. This paper compares the strength of the Dannevirke record in terms of spectral accelerations with (i) the above El Centro record, (ii) the Matahina dam record of the 1987 Edgecumbe earthquake, and (iii) the loadings of the 1984 and 1992 New Zealand codes. Also described in the paper are time-history analyses of one- and two- storey buildings subjected to the above ground motions in an attempt to explain why the damage levels were lower than might be expected from the strength of the recorded accelerograms. Comparisons are made of the seismic performance of moment-resisting frames and walled structures. Comments are made on two of the provisions of the 1992 loadings code.
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Dowrick, D. J., D. A. Rhoades y P. N. Davenport. "Damage ratios for domestic property in the magnitude 7.2 1968 Inangahua, New Zealand, earthquake". Bulletin of the New Zealand Society for Earthquake Engineering 34, n.º 3 (30 de septiembre de 2001): 191–213. http://dx.doi.org/10.5459/bnzsee.34.3.191-213.
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An analysis of damage costs to domestic property in the Mw 7.2 Inangahua, New Zealand, earthquake of 23 May 1968 (U.T.) has allowed the evaluation of the vulnerability of domestic property for six intensity zones, from MM5 - MM10 inclusive. For no other earthquake worldwide has the vulnerability of any class of property been examined in so many intensity zones, and the effect of brittle chimneys on damage levels has been fully evaluated for the first time. The relative vulnerability of one and two storey houses has also been evaluated. The costs of damage were derived from about 8,000 insurance claims to the Earthquake and War Damage Commission. Damage ratios were evaluated for houses and their contents as functions of Modified Mercalli intensity. The indicators of vulnerability that were determined were the statistical distributions and mean values of damage ratios and the percentage of property items damaged for the six intensity zones. Comparisons have also been made with results from studies of other earthquakes.
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Dowrick, David. "The serviceability of normal-use, non-domestic buildings in earthquakes". Bulletin of the New Zealand Society for Earthquake Engineering 39, n.º 4 (31 de diciembre de 2006): 208–14. http://dx.doi.org/10.5459/bnzsee.39.4.208-214.
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This paper reports on an empirical study of whether it is necessary to carry out design checks on the serviceability of normal-use non-domestic buildings in earthquakes in New Zealand. It is found that at the relevant hazard level, i.e. at a return period of 25 years, the highest intensity anywhere in New Zealand is Modified Mercalli VII (MM7). At that intensity, no loss of function (predictable by a serviceability design check) has been reported in any structures classified as Buildings Type III (brittle) or better, since the introduction of reinforced concrete construction. For normal-use non-domestic structures designed for the ultimate limit state earthquake loading, the author contends (with one interim proviso affecting 10 percent of the country) that serviceability can be deemed to be satisfactory for new buildings anywhere in the New Zealand.
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Weaver, Konrad C., R. Arnold, C. Holden, J. Townend y S. C. Cox. "A Probabilistic Model of Aquifer Susceptibility to Earthquake-Induced Groundwater-Level Changes". Bulletin of the Seismological Society of America 110, n.º 3 (12 de mayo de 2020): 1046–63. http://dx.doi.org/10.1785/0120180278.
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ABSTRACT A probabilistic model for earthquake-induced persistent groundwater-level response as a function of peak ground velocity (PGV) has been constructed using a catalog of monitoring well observations spanning multiple earthquakes. The regional-scale, multi-site, multi-earthquake investigation addresses the occurrence and absence of hydraulic responses to large earthquakes spanning almost a decade of seismic shaking. Persistent groundwater-level changes, or absences of change, have been quantified in 495 monitoring wells in response to one or more of 11 recent New Zealand earthquakes larger than Mw 5.4 that occurred between 2008 and 2017. A binary logistic regression model with random effects has been applied to the dataset using three predictors: earthquake shaking (PGV), degree of hydrogeological confinement (monitoring well depth), and rock strength (site-average shear-wave velocity). Random effects were included as a partial proxy for variations in monitoring wells’ susceptibilities to earthquake-induced persistent water-level changes. Marginal probabilities have been calculated as a function of PGV and related to modified Mercalli intensity (MMI) levels using a New Zealand-specific MMI–PGV relationship that enables the likelihood of persistent water-level changes to be expressed for MMIs of II–VIII. This study capitalizes on one of the largest catalogs of earthquake hydrological observations compiled worldwide and is the first attempt at incorporating seismic and hydrogeological factors in a common probabilistic description of earthquake-induced groundwater-level changes. This modeling framework provides a more generalizable approach to quantifying responses than alternative metrics based on epicentral distance, magnitude, and seismic energy density. It has potential to enable better comparison of international studies and to inform practitioners making engineering or investment decisions to mitigate risk and increase the resilience of water-supply infrastructure.
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Dowrick, D. J. y D. A. Rhoades. "Damage ratios for plant, equipment and stock in the 1987 Edgecumbe, New Zealand earthquake". Bulletin of the New Zealand Society for Earthquake Engineering 28, n.º 4 (31 de diciembre de 1995): 265–78. http://dx.doi.org/10.5459/bnzsee.28.4.265-278.
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This paper describes an analysis of damage costs to commercial and industrial equipment (plant) and stock in the Mw=6.6 Edgecumbe, New Zealand, earthquake of 2 March 1987. The damage costs were converted to damage ratios by dividing by the value of the relevant property parcel. The mean value and statistical distribution of damage ratios were found for various classes of equipment and stock in the MM7 and MM9 intensity Zones. The lognormal distribution generally fitted the data well.
Equipment and stock are much more variable in nature than modern buildings, and in large part are not designed for earthquakes. In this study they were analysed in subsets formed by classification according to Use (i.e. shops, offices, halls, residential or industrial) and Vulnerability (i.e. Robust, Medium or Fragile). These classifications provided useful insights into variations in the damage ratio. The overall mean damage ratio, Drm for stock was considerably higher than for equipment, even though Drm for Fragile equipment was higher than Drm for Fragile stock. This occurred because the proportion of stock that was Fragile was much larger than the corresponding proportion of equipment. The proportional difference in damage levels between Fragile and Robust property was greater at intensity MM7 than at MM9. This is consistent with the definitions of the Modified Mercalli scale. A comparison of the damage to equipment and buildings showed that, at MM9, the mean and distribution of damage ratios for Medium vulnerability equipment are similar to those for the associated single storey, post-code (1935+) commercial and industrial buildings.
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Thapa, Laxmi, Shrijana Panta, Sanjeev Kumar Raut, Florencia Mana Tuladhar, Janak Raj Joshi, Nawaraj Shrestha, Prashant Ghimire y Anish Joshi. "Multihazard Mapping of Banepa and Panauti Municipalities". Journal on Geoinformatics, Nepal 13 (13 de marzo de 2017): 25–31. http://dx.doi.org/10.3126/njg.v13i0.16934.
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A combination of rough topography, steep slopes, active tectonic and seismic process and intense impact of monsoon rain has made the fragile environment of Nepal vulnerable to a variety of natural hazards. Most frequent hazards are floods, landslides, epidemics, fires, earthquake and other hydro-meteorological disasters, causing heavy loss of human lives as well as economic loss including housing and infrastructures (MDRIP, 2009). Hence, hazard assessments are the need of the hour. They help district and regional decision makers, policy makers and development agencies prepare disaster risk reduction plans. The chosen study area was Banepa and Panauti municipality. Separate hazard assessments have been performed for four hazards, namely, earthquake, flood, landslide and industrial hazards.Earthquake hazard zone maps have been made following the Probabilistic Seismic Hazard Assessment (PSHA) approach for 500 year return period to produce seismic intensity distribution maps in the form of Modified Mercalli Intensity (MMI) maps using Trifunac and Brady formula. Flood inundation maps have been made using HEC-RAS and HEC-GeoRAS extension for ArcGIS for return periods of 2, 10 and 500 of Chandeswori and Punyamata rivers. Landslide hazard susceptibility map has been made using the Stability Index Mapping (SINMAP) extension for ArcGIS that uses an infinite-slope equation accurate for debris flows. Industrial hazard maps that depict the vicinity that falls within various ranges of danger in the event of different industrial hazards like fire, Vapor Cloud Explosion (VCE) and Boiling Liquid Expanding Vapor Explosion (BLEVE) have been prepared as well. Finally, a composite multi hazard map has been prepared by combining all the four hazards.Nepalese Journal on Geoinformatics -13, 2014, Page: 25-31
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Assumpção, Marcelo y Alberto V. Veloso. "The 1885 M 6.9 Earthquake in the French Guiana–Brazil Border: The Largest Midplate Event in the Nineteenth Century in South America". Seismological Research Letters 91, n.º 5 (20 de mayo de 2020): 2497–510. http://dx.doi.org/10.1785/0220190325.
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Abstract In 4 August 1885, 06:30 local time, a strong earthquake (reported intensities up to VI–VII modified Mercalli intensity [MMI]) was felt in the French Guiana, causing slight damage. Recently discovered newspaper records show that this event was also felt as far as Georgetown (British Guyana), Belém, and several other localities along the Amazon River toward Manaus (Brazil). The distribution of intensities and the radius of the felt area indicate a magnitude around Mw 6.9, which makes it the largest known earthquake in the stable continental region of South America, since the nineteenth century. The epicenter, determined with four different attenuation relations, lies onshore near the border between the French Guiana and Brazil, although an epicenter offshore in the continental slope cannot be ruled out with 95% confidence. The epicenter (03.4° N, 52.9°W±100 km) likely lies in the Transamazonian (2.2–2.0 Ga) geochronological province in the Guyana shield of the Amazon craton. No nearby failed rift is known onshore near the epicenter, which would place this event in the ∼30% class of nonextended stable continental crust. Other nearby smaller earthquakes (both historical and instrumental) with magnitudes up to mb 5.2, indicate a cluster of seismicity in the region of the 1885 earthquake, possibly delineating an onshore seismic zone separate from the sparse seismicity along the continental shelf. This large midplate earthquake will likely affect future reevaluations of seismic hazard in midplate South America.
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Lamontagne, Maurice y Allison L. Bent. "Earthquakes in the Eastern Canadian Arctic: Past Occurrences, Present Hazard, and Future Risk". Seismological Research Letters 92, n.º 5 (5 de mayo de 2021): 2824–37. http://dx.doi.org/10.1785/0220210014.
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Abstract The Canadian Arctic encompasses several active seismic areas where a small number of significant earthquakes have been recorded since the early twentieth century. Our study area is defined as the eastern Canadian Arctic, an immense territory that covers 30% of the Canadian land mass. It includes the territory of Nunavut and the region of Nunavik in northern Quebec. Ten earthquakes had a moment magnitude (M) between 5.5 and 7.4, but only five can be considered significant because of their impact. Most were felt in communities at distances of a few hundreds of kilometers, but none exceeded modified Mercalli intensity (MMI) V. This article contains descriptions of the impact of these five earthquakes and of smaller ones that were felt in nearby communities. These macroseismic effects suggest stronger attenuation of MMIs than what is generally assumed for eastern North America. According to the current seismic zoning, very few communities face a significant earthquake hazard. Seismic risk has to consider that most high Arctic buildings are built on piles sitting on permafrost. It is believed that the newer engineered constructions would resist fairly well to seismic shaking, as opposed to buildings with older at grade foundations with little lateral resistance. The fast warming of the Arctic may lead to some thickening of the active layer of the permafrost, which may increase the potential for slope instabilities during earthquake shaking. The change would not be significant enough to alter the potential for local ground-motion amplification.
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Thenhaus, Paul C., Stanley L. Hanson, Ismet Effendi, Engkon K. Kertapati y S. T. Algermissen. "Pilot Studies of Seismic Hazard and Risk in North Sulawesi Province, Indonesia". Earthquake Spectra 9, n.º 1 (febrero de 1993): 97–120. http://dx.doi.org/10.1193/1.1585707.
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Earthquake ground motions in North Sulawesi on soft soil that have a 90 percent probability of not being exceeded in 50 years are estimated to be 0.63 g (63 percent of the acceleration of gravity) at Palu, 0.31 g at Gorontalo, and 0.27 g at Manado. Estimated ground motions for rock conditions for the same probability level and exposure time are 56 percent of those for soft soil. The hazard estimates are obtained from seismic sources that model the earthquake potential to a depth of 100 km beneath northern and central Sulawesi and include the Palu fault zone of western Sulawesi, the North Sulawesi subduction zone, and the southern most segment of the Sangihe subduction zone beneath the Molucca Sea. An attenuation relation based on Japanese strong-motion data and considered appropriate for subduction environments of the western Pacific was used in determination of ground motions. Field investigations following the 18 April 1990 North Sulawesi earthquake (Ms 7.3) established the Modified Mercalli intensity (MMI) distribution throughout Kodya Gorontalo (the mayorial province of Gorontalo). The total number of masonry houses (permanent and semipermanent dwellings) within the MMI V isoseismal was approximated from housing counts obtained from a sampling of 19 villages. From the post-earthquake damage investigation and from comparisons to masonry construction in the United States, a vulnerability curve was constructed for masonry housing in Gorontalo. Assuming an average value for a house of $1,053, total economic loss to masonry housing from the 18 April 1990 earthquake is estimated to be $1,198,578, a loss equivalent to the destruction of 9.6 percent of the masonry dwelling stock of Gorontalo. Simulation of the earthquake history for the past 31 years within 300 km of Gorontalo indicates an average annual loss to masonry housing of $358,609, or $30 on a per house basis. Catastrophe potential (a worst-case loss) for masonry housing in Gorontalo that has a 90 percent probability of not being exceeded in 250 years is estimated to be $3,083,525, a loss equivalent to the destruction of 25 percent of the masonry dwelling stock of Gorontalo.
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Khalil, Ahmed Bakr, Mostafa Toni, Awad Hassoup y Khamis Mansour. "Analysis of aeromagnetic data for interpretation of seismicity at Fayoum-Cairo area, Egypt". Earth Sciences Research Journal 18, n.º 1 (11 de diciembre de 2014): 7–13. http://dx.doi.org/10.15446/esrj.v18n1.36938.
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<p>An aeromagnetic reconnaissance study is presented to delineate the subsurface structure and tectonic setting at the Fayoum-Cairo district, which experienced a damaging earthquake on October 12, 1992 of magnitude (M = 5.7). Analysis of aeromagnetic and seismicity data demonstrate three significant tectonic faults with trending to the NE-SW, NW-SE and E-W. The basement is uplifted in the northern and central parts with a depth of 1.3 km, and deepening in the southern part with a depth of 2.5 km. This is a seismically active zone and historically has experienced damaging earthquakes. In 1847, a damaging earthquake with maximum epicentral intensity (Modified Mercalli Intensity (MMI) = VII) was located there. On the eastern side, earthquake sources are well recognized at different locations. These sources created events of moderate size magnitude M < 5. The focal mechanisms of the major events from these sources are generally strike-slip with normal component. The focal mechanism of the earthquake on October 12, 1992 is normal fault type with strike trends in the NW-SE direction. These fault plane solutions are consistent with the tectonic trends derived from the aeromagnetic data mentioned above and suggest that the new tectonics of northeast Africa is predominant. </p><p> </p><p><strong>Resumen</strong></p><p> </p><p>Este estudio presenta una exploración aeromagnética para delimitar la estructura subsuperficial y el marco tectónico del distrito de Fayoum-Cairo, que sufrió un terremoto el 12 de octubre de 1992 de magnitud M=5.7. Los análisis de datos sismicidad y aeromagnéticos señalan tres fallas tectónicas significativas con tendencias NE-SO, NO-SE y E-O. El subsuelo se elevó en el norte y en el centro a una profundidad de 1,3 kilómetros, y se hundió en el sur con una profundidad de 2,5 kilómetros. Esta es una zona sísmicamente activa que en su historia ha tenido terremotos dañinos. En 1847 tuvo lugar un terremoto con intensidad epicentral máxima (escala sismológica de Mercalli) de VII. En el lado este se estudiaron las fuentes de terremotos en diferentes partes. Estas fuentes crearon eventos de magnitud moderada M<5. Los mecanismos focales de los eventos principales en estas fuentes son generalmente fallas de desgarre con componente normal. El mecanismo focal del terremoto del 12 de octubre de 1992 es una falla tipo normal con fuertes movimientos NO-SE. Las soluciones de estas fallas son consistentes con las tendencias tectónicas de los datos aeromagnéticos antes mencionados y sugieren que la nueva tectónica del noreste de África es predominante.</p>
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Dowrick, D. J. y D. A. Rhoades. "A distributed-source approach to modelling the spatial distribution of MM intensities resulting from large crustal New Zealand earthquakes". Bulletin of the New Zealand Society for Earthquake Engineering 43, n.º 2 (30 de junio de 2010): 85–109. http://dx.doi.org/10.5459/bnzsee.43.2.85-109.
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This paper presents a new approach to modelling the spatial distribution of intensities in crustal earthquakes, using a distributed source. The source is represented by one or two rectangular fault rupture planes of chosen dip, discretised into small rectangles each with its own share of the total seismic moment, and modelling chosen distributions of asperities. The Modified Mercalli (MM) intensity of shaking is represented by isoseismals. Comparisons are made with the actual isoseismals (particularly of intensities MM9 and MM10) of selected large historical crustal New Zealand earthquakes and those predicted by the simpler models of Dowrick & Rhoades (2005). Important differences and insights are found regarding near-source spatial distributions of ground shaking of shallow earthquakes with rupture length greater than about 28 km (Mw > 6.8) with any dip, and for Mw > c. 5.5 with dip < 60º. The influence of asperities relative to that of non-asperities is seen as modest near-fault increases in intensity. The new model can be applied to planar or biplanar fault ruptures of any length, width and dip. In the absence of isoseismal data on large earthquakes with normal focal mechanisms the current model is only verified for use on strike-slip and reverse events. A new concept, seismic-source intensity, is introduced and utilized.
The new model can also be applied to earthquakes in other regions of the world with adjustments for local attenuation rates as necessary.
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Han, Ju, Arip Nur, Mutiara Syifa, Minsu Ha, Chang-Wook Lee y Ki-Young Lee. "Improvement of Earthquake Risk Awareness and Seismic Literacy of Korean Citizens through Earthquake Vulnerability Map from the 2017 Pohang Earthquake, South Korea". Remote Sensing 13, n.º 7 (2 de abril de 2021): 1365. http://dx.doi.org/10.3390/rs13071365.
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Earthquake activities in and around the Korean Peninsula are relatively low in number and intensity compared with neighboring countries such as Japan and China. However, recent seismic activity caused great alarm and concern among citizens and government authorities, and uncovered the level of preparedness toward earthquake disasters. A survey has been conducted on 1256 participants to investigate the seismic literacy of Korean citizens, including seismic knowledge, awareness and management using a questionnaire of citizen earthquake literacy (CEL). The results declared that the citizens had low awareness and literacy, which means that they are not properly prepared for earthquake hazards. To develop an earthquake risk reduction plan and program efficiently and effectively, not only must it appropriately characterize the target audience, but also indicate high potential earthquake zones and potential earthquake damage. Therefore, this study mapped and analyzed the seismic vulnerability in southeast Korea using LogitBoost, logistic model tree (LMT), and logistic regression (LR) machine learning algorithms based on a building damage inventory map. The damaged buildings’ locations were generated after the 2017 Pohang earthquake using the damage proxy map (DPM) method from the Sentinel-1 synthetic aperture radar (SAR) data. DPMs detected coherence loss, which indicates damaged buildings in urban areas in the Pohang earthquake and shows a good correlation with the Korea Meteorological Administration (KMA) report with modified Mercalli intensity (MMI) scale values of more than VII (seven). The damage locations were randomly divided into two datasets: 50% for training the vulnerability models and 50% for validating the models in terms of accuracy and reliability. Fifteen seismic-related factors were used to construct a model of each algorithm. Model validation based on the area under the receiver operating curve (AUC) was used to determine model accuracy. The AUC values of seismic vulnerability maps using the LogitBoost, LMT, and LR algorithms were 0.769, 0.851, and 0.749, respectively. We suggest that earthquake preparedness efforts should focus on reconstruction, retrofitting, renovation, and seismic education in areas with high seismic vulnerability in South Korea. The results of this study are expected to be beneficial for engineers and policymakers aiming at developing disaster risk reduction plans, policies, and programs due to future seismic activity in South Korea.
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Atkinson, G. M. "Empirical Relationships between Modified Mercalli Intensity and Response Spectra". Bulletin of the Seismological Society of America 90, n.º 2 (1 de abril de 2000): 537–44. http://dx.doi.org/10.1785/0119990118.
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Dowrick, D. J. y D. A. Rhoades. "Attenuation of Modified Mercalli intensity in New Zealand earthquakes". Bulletin of the New Zealand Society for Earthquake Engineering 32, n.º 2 (30 de junio de 1999): 55–89. http://dx.doi.org/10.5459/bnzsee.32.2.55-89.
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The main result of this study is the development of attenuation expressions for Modified Mercalli intensity isoseismals in New Zealand earthquakes, in terms of magnitude Mw and source distance. Attenuation of isoseismal intensities has been modelled in a new 2-dimensional manner, i.e. in terms of three distance measures, i.e. radius a along the strike of the fault rupture, radius b normal to strike, and the mean radius c. Other factors which are included in the modelling are depth, focal mechanism, tectonic type (i.e. crustal, interface or dipping slab), and regional variations. As well as being implied in the source distance, the moderate effect of depth (to increase intensities) is modelled well with a separate linear depth term. Shallow (hc ≤ 60 km) Reverse mechanism events were found to give stronger intensities than Strike-Slip events which in tum were stronger than Normal mechanism events, the difference near source between Reverse and Normal events of Mw 7+ events being about 0.4 intensity units. Attenuation for the Central Volcanic Region and Deep events differs markedly from the Main Seismic Region. No magnitude saturation effects were found. Comparisons are made with some earlier New Zealand intensity models, and local and international peak ground acceleration attenuation models.
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Editor. "A revision of the Modified Mercalli seismic intensity scale". Bulletin of the New Zealand Society for Earthquake Engineering 25, n.º 4 (31 de diciembre de 1992): 345–57. http://dx.doi.org/10.5459/bnzsee.25.4.345-357.
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Dowrick, David J. "Attenuation of modified mercalli intensity in New Zealand earthquakes". Earthquake Engineering & Structural Dynamics 21, n.º 3 (1992): 181–96. http://dx.doi.org/10.1002/eqe.4290210301.
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Chávez, Mario y Raul Castro. "Attenuation of modified Mercalli intensity with distance in Mexico". Bulletin of the Seismological Society of America 78, n.º 6 (1 de diciembre de 1988): 1875–84. http://dx.doi.org/10.1785/bssa0780061875.
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Abstract Two relations are proposed to predict the attenuation of Modified Mercalli Intensity (I) with distance (D) for Mexican earthquakes, i.e. ln I = B 0 + B 1 ln ( D / D ' ) + B 2 ( D − D ' ) + B 3 ln M s ln I = B 0 + B 1 ( D / D ' ) + B 2 ln ( D − D ' ) + B 3 ln M s Ms is the earthquake surface-wave magnitude, D′ is a distance related to the maximum I mapped for an earthquake, I′ or to Ms. The coefficients Bi, i = 0, 1, 2, 3 were obtained by fitting in a least-square sense the information contained in the intensity maps of 32 events to the relations. Those events were classified in three groups according to their epicentral location, focal mechanism, and depth, i.e., events related to the subduction-zone intermediate-depth earthquakes in south-central Mexico and to shallow crustal events along the Trans-Mexican Volcanic Belt. The I predicted by the proposed relations compare well with the I observed for historical earthquakes not included in the fitting. Results obtained from a parametrical study showed that the attenuation of I with D is different for each of the three types of earthquakes. For distances of less than about 200 km, the earthquakes associated with the subduction zone have a larger attenuation than the ones originating in the south-central region of Mexico; for greater distances (D > 200 km), the opposite behavior is observed. The events located in the Trans-Mexican Volcanic Belt have a larger attenuation with distance than that of events in the other two regions. From these results, it seems advisable in Mexico to use several attenuation relations to estimate the seismic hazard at a site, depending on the particular tectonic setting and the path of the events under consideration.
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Wald, David J., Vincent Quitoriano, Thomas H. Heaton y Hiroo Kanamori. "Relationships between Peak Ground Acceleration, Peak Ground Velocity, and Modified Mercalli Intensity in California". Earthquake Spectra 15, n.º 3 (agosto de 1999): 557–64. http://dx.doi.org/10.1193/1.1586058.
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We have developed regression relationships between Modified Mercalli Intensity ( Imm) and peak ground acceleration (PGA) and velocity (PGV) by comparing horizontal peak ground motions to observed intensities for eight significant California earthquakes. For the limited range of Modified Mercalli intensities ( Imm), we find that for peak acceleration with V ≤ Imm ≤ VIII, Imm = 3.66 log( PGA) − 1.66, and for peak velocity with V ≤ Imm ≤ IX, Imm = 3.47 log( PGV) + 2.35. From comparison with observed intensity maps, we find that a combined regression based on peak velocity for intensity > VII and on peak acceleration for intensity < VII is most suitable for reproducing observed Imm patterns, consistent with high intensities being related to damage (proportional to ground velocity) and with lower intensities determined by felt accounts (most sensitive to higher-frequency ground acceleration). These new Imm relationships are significantly different from the Trifunac and Brady (1975) correlations, which have been used extensively in loss estimation.
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Leyendecker, E. V., L. M. Highland, M. Hopper, E. P. Arnold, P. Thenhaus y P. Powers. "The Whittier Narrows, California Earthquake of October 1, 1987—Early Results of Isoseismal Studies and Damage Surveys". Earthquake Spectra 4, n.º 1 (febrero de 1988): 1–10. http://dx.doi.org/10.1193/1.1585458.
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Preliminary isoseismals for Modified Mercalli intensities are presented for the Whittier Narrows Earthquake. Isoseismals for intensities VI and lower are based on responses to a mail survey. Intensity VII and larger are based on a field survey of damage described in this paper. The maximum observed intensity of VIII was confined to Whittier. The shapes of the intensity contours compare favorably with the distribution of average peak acceleration data from the strong motion array in the greater Los Angeles area. The damage assessments appeared consistent with earthquake magnitude. However, the accelerations were higher than expected for the magnitude. The building classification and survey strategies developed were tested and found usable and adequate for describing damage. With further refinement this system can be used to describe damage within a limited geographical area and in a format useful for correlations with strong ground motions and the Modified Mercalli Intensity scale.
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Pailoplee, Santi. "Relationship between Modified Mercalli Intensity and peak ground acceleration in Myanmar". Natural Science 04, n.º 08 (2012): 624–30. http://dx.doi.org/10.4236/ns.2012.428082.
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Yaghmaei-Sabegh, Saman, Hing-Ho Tsang y Nelson T. K. Lam. "Conversion between Peak Ground Motion Parameters and Modified Mercalli Intensity Values". Journal of Earthquake Engineering 15, n.º 7 (septiembre de 2011): 1138–55. http://dx.doi.org/10.1080/13632469.2011.565861.
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