Journal articles: 'Magnitude estimates'

1

HIGASHIYAMA, ATSUKI, and TAKARA TASHIRO. "Magnitude estimates for electrical shock." Japanese Psychological Research 29, no. 2 (1987): 81–88. http://dx.doi.org/10.4992/psycholres1954.29.81.

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2

Albarello, D., A. Berardi, C. Margottini, and M. Mucciarelli. "Macroseismic estimates of magnitude in Italy." Pure and Applied Geophysics PAGEOPH 145, no. 2 (November 1995): 297–312. http://dx.doi.org/10.1007/bf00880272.

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Paap, Bob, and Philippe Steeghs. "Calibration of a local magnitude relationship for microseismic events using earthquake data." GEOPHYSICS 81, no. 2 (March 1, 2016): KS61—KS70. http://dx.doi.org/10.1190/geo2014-0598.1.

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Calibration of local seismic arrays is crucial to quantify the magnitude of local microseismic events. This is traditionally done by performing a site survey consisting of calibration shots at known locations with known strength. However, when a calibration survey cannot be conducted, alternative calibration methods are required. We have demonstrated the feasibility of magnitude estimation of microseismic events recorded at the [Formula: see text] storage site at Ketzin (Germany), by analyzing earthquake signals that have been recorded on the noncalibrated geophone array and on standardized seismometers of a regional seismological network. We estimated a linear calibration relation by fitting three different signal attributes for 10 distant earthquakes. Through extrapolation of the linear fit toward lower magnitudes, we estimated the local magnitude of weak local seismic events. Reported magnitudes of the distant earthquakes show significant variation because there are different methods and constants used to calculate a magnitude estimate from recordings on multiple seismometers. As a consequence, there was a considerable spread in our magnitude estimates for the Ketzin events. We found magnitude values in the range between [Formula: see text] and [Formula: see text] for two local events recorded at the Ketzin site. We expect that by incorporating additional distant earthquake data, the uncertainty in this estimate can be further reduced.

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Ristau, J. "Comparison of Magnitude Estimates for New Zealand Earthquakes: Moment Magnitude, Local Magnitude, and Teleseismic Body-Wave Magnitude." Bulletin of the Seismological Society of America 99, no. 3 (June 1, 2009): 1841–52. http://dx.doi.org/10.1785/0120080237.

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Wanninkhof, R., G. H. Park, T. Takahashi, C. Sweeney, R. Feely, Y. Nojiri, N. Gruber, et al. "Global ocean carbon uptake: magnitude, variability and trends." Biogeosciences Discussions 9, no. 8 (August 15, 2012): 10961–1012. http://dx.doi.org/10.5194/bgd-9-10961-2012.

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Abstract. Estimates of the anthropogenic global-integrated sea-air carbon dioxide (CO2) flux from 1990 to 2009, based on different models and measurements, range from –1.4 to –2.6 Pg C yr–1. The median values of anthropogenic CO2 for each method show better agreement and are: −1.9 for Pg C yr−1 for numerical ocean general circulation hind cast models (OGCMs) with parameterized biogeochemistry; –2.1 Pg C yr–1 for atmospheric inverse models; –1.9 Pg C yr–1 for global atmospheric constraints based on O2 / N2 ratios for 1990–2000; and –2.4 Pg C yr–1 for oceanic inverse models. An updated estimate of this anthropogenic CO2 flux based on a climatology of sea-air partial pressure of CO2 differences (ΔpCO2) (Takahashi et al., 2009) and a bulk formulation of gas transfer with wind speed for year 2000 is –2.0 Pg C yr–1. Using this ΔpCO2 climatology and empirical relationships of pCO2 with sea-surface temperature (SST) anomalies (Park et al., 2010a), the interannual variability of the contemporary CO2 flux is estimated to be 0.20 Pg C yr–1 (1σ) from 1990 through 2009. This is similar to the variability estimated by the OGCMs of 0.16 Pg C yr–1 but smaller than the interannual variability from atmospheric inverse estimates of 0.40 Pg C yr–1. The variability is largely driven by large-scale climate re-organizations. The decadal trends for different methods range from –0.13 (Pg C yr–1) decade–1 to –0.50 (Pg C yr−1) decade−1. The OGCMs and the data based sea-air CO2 flux estimates show smaller uptakes and appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. It is not clear if this large difference in trend is a methodological issue or a real natural feedback.

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Stephens, B. R., and J. L. Dannemiller. "Decruitment effects for magnitude estimates of pattern contrast." Journal of Vision 2, no. 7 (March 15, 2010): 194. http://dx.doi.org/10.1167/2.7.194.

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Weismer, Gary, and Jacqueline S. Laures. "Direct Magnitude Estimates of Speech Intelligibility in Dysarthria." Journal of Speech, Language, and Hearing Research 45, no. 3 (June 2002): 421–33. http://dx.doi.org/10.1044/1092-4388(2002/033).

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Ma, Qingxia, Zhen Yang, and Zhijie Zhang. "The Modulation of Implicit Magnitude on Time Estimates." PLoS ONE 7, no. 10 (October 15, 2012): e46471. http://dx.doi.org/10.1371/journal.pone.0046471.

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Wang, S., and M. Tang. "Exact Confidence Interval for Magnitude-Squared Coherence Estimates." IEEE Signal Processing Letters 11, no. 3 (March 2004): 326–29. http://dx.doi.org/10.1109/lsp.2003.822897.

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Bender, Bernice. "Effects of observational errors in relating magnitude scales and fitting the gutenberg-richter parameter β." Bulletin of the Seismological Society of America 77, no. 4 (August 1, 1987): 1400–1428. http://dx.doi.org/10.1785/bssa0770041400.

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Abstract In order to use historic earthquakes to estimate future seismicity of a region, the analyst usually first converts earthquake sizes that have been recorded in various ways (e.g., mb, MS, ML, and I0) to a common scale (e.g., mb), by fitting the coefficients ai and bi in an assumed linear relationship mb = ai + bimi between mb and each of the other size measures mi. He then combines mb values (either recorded mb or fitted m^b) for all earthquakes to estimate a Gutenberg-Richter rate parameter, αmb, and distribution parameter, βmb. However, even if magnitude scales are linearly related over some range, when observational errors are present and earthquakes have been incompletely recorded at lower magnitudes or terminate abruptly at some finite mmax, estimates âi, b^i may be highly biased and uncertain. Less biased estimates of b^i can be obtained if only magnitude values in the interior of the range are used in the fitting. Errors in b^i carry over into estimates βmb(i) obtained using magnitudes converted to m^b from mi. This means that even if a large number, N, of mi values are converted to mb values, the variance of β^mb(i) using these magnitudes may depend primarily on the sizes of the observational errors and on n the number, of pairs (mb and mi) used to fit b^i, rather than on N. An estimate βmb(i) may be obtained without converting magnitudes mi to mb by estimating β^i (the distribution parameter for mi) using the N mi values and then setting β^mb(i)=β^i/b^i. Individual estimates 1/βmb(i) for various scales, mi, may be weighted and combined, and then inverted to obtain an estimate of βmb that has a lower variance than does the estimate obtained using all the earthquakes simultaneously. This study particularly considers estimates involving I0, epicentral intensity, because often I0 is the only size recorded for an earthquake. A relatively large range of magnitudes corresponds to a single intensity, making the analysis more complicated for this case.

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11

Eken, Tuna. "Moment magnitude estimates for central Anatolian earthquakes using coda waves." Solid Earth 10, no. 3 (May 23, 2019): 713–23. http://dx.doi.org/10.5194/se-10-713-2019.

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Abstract. A proper estimate of moment magnitude, which is a physical measure of the energy released at an earthquake source, is essential for better seismic hazard assessments in tectonically active regions. Here a coda wave modeling approach that enables the source displacement spectrum modeling of the examined event was used to estimate moment magnitudes of central Anatolia earthquakes. To achieve this aim, three-component waveforms of local earthquakes with magnitudes 2.0≤ML≤5.2 recorded at 69 seismic stations, which were operated between 2013 and 2015 within the framework of the Continental Dynamics–Central Anatolian Tectonics (CD–CAT) passive seismic experiment, were utilized. An inversion on the coda wave traces of each selected single event in the database was performed in five different frequency bands between 0.75 and 12 Hz. The resultant moment magnitudes (Mw coda) exhibit a good agreement with routinely reported local magnitude (ML) estimates for the study area. Apparent move-out that is particularly significant around the scattered variation of ML–Mw coda data points for small earthquakes (ML < 3.5) can be explained by possible biases of wrong assumptions to account for anelastic attenuation and seismic recordings with a finite sampling interval. Finally, I present an empirical relation between Mw coda and ML for central Anatolian earthquakes.

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Zúñiga, F. Ramón, and Max Wyss. "Inadvertent changes in magnitude reported in earthquake catalogs: Their evaluation through b-value estimates." Bulletin of the Seismological Society of America 85, no. 6 (December 1, 1995): 1858–66. http://dx.doi.org/10.1785/bssa0850061858.

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Abstract A simple procedure is presented for analyzing magnitudes and seismicity rates reported in earthquake catalogs in order to discriminate between inadvertently introduced changes in magnitude and real seismicity changes. We assume that the rate and the frequency-magnitude relation of the independent background seismicity do not change with time. Observed differences in the frequency-magnitude relation (a and b values) between data from two periods are modeled as due to a transformation of the magnitude scale. The transformation equation is found by a least-squares-fitting process based on the seismicity data for earthquakes large enough to be reported completely and by comparing the linear relation of one period to the other. For smaller events, an additional factor accounting for increased (decreased) detection is allowed. This fitting technique is tested on a data set from Parkfield for which two types of magnitudes, amplitude and duration, were computed for each earthquake. We found that the b-value fitting technique yielded virtually the same result as a linear regression assuming the same errors in the two magnitudes. The technique is also applied to interpret the nature of reporting rate changes in a local (Guerrero, Mexico) and a regional (Italy) earthquake catalog. In Guerrero, a magnitude change in 1991.37 can be modeled about equally well by Mnew = Mold + 0.5 or by Mnew = 1.02 Mold + 0.38, but residuals with the latter transformation are smaller. In Italy, a magnitude change in 1980.21 cannot be modeled satisfactorily by a simple magnitude shift but is well described by a compression of the magnitude scale given by Mnew = 0.67 Mold + 1.03. The proposed b-slope fitting method provides a means to interpret quantitatively, and in some cases correct for, artificial reporting rate changes in earthquake catalogs.

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13

Wanninkhof, R., G. H. Park, T. Takahashi, C. Sweeney, R. Feely, Y. Nojiri, N. Gruber, et al. "Global ocean carbon uptake: magnitude, variability and trends." Biogeosciences 10, no. 3 (March 22, 2013): 1983–2000. http://dx.doi.org/10.5194/bg-10-1983-2013.

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Abstract. The globally integrated sea–air anthropogenic carbon dioxide (CO2) flux from 1990 to 2009 is determined from models and data-based approaches as part of the Regional Carbon Cycle Assessment and Processes (RECCAP) project. Numerical methods include ocean inverse models, atmospheric inverse models, and ocean general circulation models with parameterized biogeochemistry (OBGCMs). The median value of different approaches shows good agreement in average uptake. The best estimate of anthropogenic CO2 uptake for the time period based on a compilation of approaches is −2.0 Pg C yr−1. The interannual variability in the sea–air flux is largely driven by large-scale climate re-organizations and is estimated at 0.2 Pg C yr−1 for the two decades with some systematic differences between approaches. The largest differences between approaches are seen in the decadal trends. The trends range from −0.13 (Pg C yr−1) decade−1 to −0.50 (Pg C yr−1) decade−1 for the two decades under investigation. The OBGCMs and the data-based sea–air CO2 flux estimates show appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. RECCAP model outputs for five decades show similar differences in trends between approaches.

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Kishida, Tadahiro, Sahar Derakhshan, Sifat Muin, Robert B. Darragh, Yousef Bozorgnia, Nicolas Kuehn, and Dong Youp Kwak. "Multivariate Conversion of Moment Magnitude for Small-to-Moderate-Magnitude Earthquakes in Iran." Earthquake Spectra 34, no. 1 (February 2018): 313–26. http://dx.doi.org/10.1193/050917eqs086m.

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Homogeneous estimates of moment magnitude (M) for small-to-moderate-magnitude (SMM) earthquakes are important to assess regional ground motion compared to global models. However, an estimate of M was available for only 6% of the shallow crustal earthquakes in Iran from 1973 to 2013 in the database developed by the Pacific Earthquake Engineering Research Center. Therefore, this study evaluates the existing conversion models, from ML, Ms, and m b, to M, for M > 4.0 using the Iranian data set. Correlations between the residuals of these conversions were computed. A weighted estimate for M is presented that combines these conversion models using these correlations based on multivariate statistics. The conversion to M was improved with smaller standard deviations, especially when ML and m b were both available. The inverse-variance–weighted approach, which is common in practice, underestimates the standard deviations because it neglects the positive correlations between these variables.

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Young, Laura K., and Julie L. Booth. "Student Magnitude Knowledge of Negative Numbers." Journal of Numerical Cognition 1, no. 1 (October 29, 2015): 38–55. http://dx.doi.org/10.5964/jnc.v1i1.7.

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Numerous studies have demonstrated the relevance of magnitude estimation skills for mathematical proficiency, but little research has explored magnitude estimation with negative numbers. In two experiments the current study examined middle school students’ magnitude knowledge of negative numbers with number line tasks. In Experiment 1, both 6th (n = 132) and 7th grade students (n = 218) produced linear representations on a -10,000 to 0 scale, but the 7th grade students’ estimates were more accurate and linear. In Experiment 2, the 7th grade students also completed a -1,000 to 1,000 number line task; these results also indicated that students are linear for both negative and positive estimates. When comparing the estimates of negative and positive numbers, analyses illustrated that estimates of negative numbers are less accurate than those of positive numbers, but using a midpoint strategy improved negative estimates. These findings suggest that negative number magnitude knowledge follows a similar pattern to positive numbers, but the estimation performance of negatives lags behind that of positives.

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Mayeda, Kevin. "mb(LgCoda): A stable single station estimator of magnitude." Bulletin of the Seismological Society of America 83, no. 3 (June 1, 1993): 851–61. http://dx.doi.org/10.1785/bssa0830030851.

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Abstract Stable single-station estimates of magnitude have been made using the 1-Hz Lg coda envelope of regionally recorded nuclear explosions from the Nevada Test Site (NTS). After empirical relations describing the Lg coda envelope were found for each NTS-station path, single station magnitudes based on the Lg coda envelope were made with precision in the range of 0.03 to 0.04 magnitude units, whereas magnitudes based on third peak Lg amplitude, rms Lg amplitude, and Pn amplitude had scatter on the order of 0.15 to 0.2 magnitude units, generally five times larger than the coda scatter. Despite the high station correlations, the magnitude-yield residuals for events above the water table using the network average mb(LgCoda) were only marginally better than the other magnitude estimates, roughly 10% smaller. Magnitude-yield residual for events above the water table between mb(LgCoda) and mb(Lg) are strongly correlated suggesting that the source region properties, such as gas porosity, affect both magnitudes. Using only a single station, the standard deviation for magnitude-yield residuals using mb(LgCoda) were roughly 25% smaller than those derived from mb(Lg) or mb(Pn). These results show that the method is ideally suited to monitoring efforts in sparsely instrumented regions where little is known about the lateral variations of medium properties.

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Penner, M. J. "Magnitude Estimation and the "Paradoxical" Loudness of Tinnitus." Journal of Speech, Language, and Hearing Research 29, no. 3 (September 1986): 407–12. http://dx.doi.org/10.1044/jshr.2903.407.

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Ten patients with sensorineural hearing loss and tinnitus matched external tones to the tinnitus pitch. These matches were followed by (a) magnitude estimates to measure the loudness function of tones at 1 kHz and at the presumed tinnitus frequency (i.e., at the average frequency matching the pitch of the tinnitus), (b) magnitude estimates of the tinnitus itself, and (c) loudness matches of external tones to the tinnitus. The slope of the loudness function at 1 kHz is substantially smaller than the slope at the presumed tinnitus frequency. Most importantly, the magnitude estimates of the tinnitus coupled with intensity matches to the tinnitus provide coordinates that typically lie near the loudness function of the external tone used in the intensity match. Because the slope of the loudness function is much greater at the tinnitus frequency than at 1 kHz, the magnitude estimate of tinnitus loudness corresponds to a lower sensation level at that frequency than at 1 kHz. This finding favors the conclusion that rapid hanges in loudness of external tones at the tinnitus frequency account for the "paradoxical" loudness of the tinnitus. The conclusion is independent of any mathematical description of the loudness function.

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Barbosa, Maria Tereza S., and Claudio J. Struchiner. "The estimated magnitude of AIDS in Brazil: a delay correction applied to cases with lost dates." Cadernos de Saúde Pública 18, no. 1 (February 2002): 279–85. http://dx.doi.org/10.1590/s0102-311x2002000100028.

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The number of HIV-infected people is an important measure of the magnitude of the AIDS epidemic in Brazil and allows for comparison with epidemic patterns in other countries. This quantity can be estimated from the number of reported AIDS cases, which in turn needs to be corrected for the distribution of reporting delays and under-recording of cases. These distributions are unknown and must also be estimated from the recorded dates, which were missed to the Brazilian National AIDS registry. This paper estimates the number of AIDS cases diagnosed by imputing the lost information based on an estimate of the pattern in registration delay until 1996. We first fitted a non-stationary bivariate Poisson regression model to estimate the pattern in reporting delay. In the subsequent steps these models were applied to impute new data, thus replacing the missing information, and to estimate the magnitude of the AIDS epidemic in the country. Model estimates ranged from 36,000 to 50,000 AIDS cases diagnosed in Brazil and still unreported. Therefore, the epidemic was 20 to 30% greater than known from the available information as of February 1999. To be useful to health policy-makers, the surveillance system based on officially reported AIDS cases must be continuously improved.

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Habermann, R. E. "A test of two techniques for recognizing systematic errors in magnitude estimates using data from parkfield, California." Bulletin of the Seismological Society of America 76, no. 6 (December 1, 1986): 1660–67. http://dx.doi.org/10.1785/bssa0760061660.

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Abstract Selections of events from seismicity catalogs on the basis of size are universally made on the basis of magnitude. Such a selection implicitly assumes that these magnitudes provide a temporally consistent measure of earthquake size or that systematic errors in magnitudes are constant. Several techniques can be used to test this assumption. Results of application of these techniques to local and teleseismic catalogs indicate that in many cases this assumption cannot be justified. Two different techniques for identifying changes in systematic errors in magnitude are described here and applied to recent seismicity data from Parkfield, California. One technique relies on comparisons of seismicity rates before and after a possible change in magnitudes. The other uses station magnitude corrections to redetermine magnitudes. Both of these techniques indicate that a systematic decrease in magnitudes by 0.18 to 0.19 units occurred at Parkfield during November 1984. This decrease was associated with the installation of six low-gain stations in the Parkfield region. It is clear that changes in stations distributions can have significant effects on magnitudes and that these changes must be accounted for in all seismicity studies which use magnitude as a selection criteria. The results of past studies which have not accounted for these changes must be reevaluated.

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Govers, R., M. J. R. Wortel, S. A. P. L. Cloetingh, and C. A. Stein. "Stress magnitude estimates from earthquakes in oceanic plate interiors." Journal of Geophysical Research 97, B8 (1992): 11749. http://dx.doi.org/10.1029/91jb01797.

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Boyd, Robert W. "Order-of-magnitude estimates of the nonlinear optical susceptibility." Journal of Modern Optics 46, no. 3 (March 1999): 367–78. http://dx.doi.org/10.1080/09500349908231277.

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Kintner, Jonas A., Charles J. Ammon, Kyle Homman, and Andrew Nyblade. "Precise Relative Magnitude and Relative Location Estimates of Low-Yield Industrial Blasts in Pennsylvania." Bulletin of the Seismological Society of America 110, no. 1 (January 14, 2020): 226–40. http://dx.doi.org/10.1785/012019163.

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ABSTRACT Low-yield explosion monitoring requires the use of nearby short-period observations, which exhibit sensitivities to geologic heterogeneity and have low signal-to-noise ratios compared to larger events. In this study, we analyze 843 seismic events using nearly 475,000 individual observations to compute precise relative locations of small (1<ML<3) industrial explosions across Pennsylvania using local shear-wave and short-period, near-regional distance shear and surface-wave observations. We show that common-station, nearby event cross-correlation time-shift measurements reduce much of the complexity in wave propagation caused by regional geological heterogeneity. The resulting high-precision relative location estimates (with formal location uncertainties of tens of meters in some cases) allow us to image the time-dependent migration of the blast wall for several mines across Pennsylvania. In areas with two or more mines, the relative locations collapse a diffuse distribution of small-magnitude industrial events into discrete clusters associated with particular mining operations. We also use cross-correlation amplitudes to estimate more precise relative event magnitudes. We find that the relative magnitudes are generally consistent with the catalog magnitudes but improve the relationship between the reported amount of explosives used and event size for several mining operations throughout Pennsylvania. This work adds to existing demonstrations of how dense regional seismic networks are valuable for small-event monitoring and characterization, while also corroborating earlier works indicating the ability of cross-correlation methods to achieve precise relative location and magnituode estimates from local and regional observations of low-yield seismic sources.

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Priestley, Keith F., and David E. Chávez. "Magnitude bias in the Great Basin and its implications for explosion magnitude versus yield estimates." Geophysical Research Letters 12, no. 9 (September 1985): 573–76. http://dx.doi.org/10.1029/gl012i009p00573.

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Kim, Won-Young, Lars Ottemöller, and Paul G. Richards. "A Regional Sn Magnitude Scale mb(Sn) and Estimates of Moment Magnitude for Earthquakes along the Northern Mid-Atlantic Ridge." Bulletin of the Seismological Society of America 110, no. 6 (August 11, 2020): 3158–73. http://dx.doi.org/10.1785/0120190304.

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ABSTRACT We present a regional short-period Sn magnitude scale mb(Sn) for small earthquakes along the northern Mid-Atlantic Ridge. Surface-wave magnitudes, teleseismic body-wave magnitudes, and seismic moments cannot be reliably determined for small earthquakes along this and other midocean ridges. Local magnitudes that rely on Lg waves are likewise not generally useful due to the substantial oceanic paths for earthquakes along midocean ridges. In contrast, Pn and Sn arrivals for earthquakes along the northern Mid-Atlantic Ridge are generally well recorded by the existing seismographic networks, and, in fact, Sn arrivals are larger than Pn arrivals for about one-third of the ridge events. For this reason, we have developed a new regional Sn magnitude scale that is tied to Mw, so that seismic moments can be readily approximated. In our least-squares fit of peak amplitudes from 120 earthquakes having a published moment magnitude, we solved for the attenuation curve for paths in the oceanic mantle lid, for event magnitude adjustments (EMAs) to account for differences between long-period moment magnitude Mw and short-period Sn magnitude, and for station corrections. We find regional EMAs that are well correlated with the style of faulting: they are positive for normal-faulting earthquakes along spreading ridges and negative for strike-slip earthquakes along transform faults. These source-specific EMAs are approximately +0.11 magnitude units for normal-fault earthquakes and −0.26 magnitude units for strike-slip earthquakes on transform faults, and are consistent with previously reported apparent stresses from these regions. The amplitude distance curve determined for Sn for the northern Atlantic Ocean is similar to that determined for Pn in the northern Atlantic out to a distance of about 500 km, but at larger distances is more similar to the western U.S. Pn curve, likely reflective of the warmer temperatures at greater upper-mantle depths.

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Farghal, Noha, Andrew Barbour, and John Langbein. "The Potential of Using Dynamic Strains in Earthquake Early Warning Applications." Seismological Research Letters 91, no. 5 (July 1, 2020): 2817–27. http://dx.doi.org/10.1785/0220190385.

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Abstract We investigate the potential of using borehole strainmeter data from the Network of the Americas (NOTA) and the U.S. Geological Survey networks to estimate earthquake moment magnitudes for earthquake early warning (EEW) applications. We derive an empirical equation relating peak dynamic strain, earthquake moment magnitude, and hypocentral distance, and investigate the effects of different types of instrument calibration on model misfit. We find that raw (uncalibrated) strains fit the model as accurately as calibrated strains. We test the model by estimating moment magnitudes of the largest two earthquakes in the July 2019 Ridgecrest earthquake sequence—the M 6.4 foreshock and the M 7.1 mainshock—using two strainmeters located within ∼50 km of the rupture. In both the cases, the magnitude based on the dynamic strain component is within ∼0.1–0.4 magnitude units of the catalog moment magnitude. We then compare the temporal evolution of our strain-derived magnitudes for the largest two Ridgecrest events to the real-time performance of the ShakeAlert EEW System (SAS). The final magnitudes from NOTA borehole strainmeters are close to SAS real-time estimates for the M 6.4 foreshock, and significantly more accurate for the M 7.1 mainshock.

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Raphael, Steven. "Estimating the Union Earnings Effect Using a Sample of Displaced Workers." ILR Review 53, no. 3 (April 2000): 503–21. http://dx.doi.org/10.1177/001979390005300308.

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This paper improves on past longitudinal estimates of the union earnings effect by using a sample of workers for whom the error in measuring changes in union status is minimized. The author uses a sample of workers displaced by plant closings from the 1994 and 1996 Current Population Survey Displaced Workers Supplement files to estimate the effects of union membership on weekly earnings. When models are estimated using the entire sample of displaced workers, longitudinal estimates of the union earnings effect are quite similar in magnitude to estimates from cross-sectional regressions. In models estimated separately by skill group, the author finds some evidence of positive selection into unions among workers with low observed skills and negative selection into unions among workers with high observed skills.

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Higashiyama, Atsuki, and Takara Tashiro. "Magnitude estimates for electrical pulses: Evidence for two neural mechanisms." Perception & Psychophysics 45, no. 6 (November 1989): 537–49. http://dx.doi.org/10.3758/bf03208061.

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Connor, CE, SS Hsiao, JR Phillips, and KO Johnson. "Tactile roughness: neural codes that account for psychophysical magnitude estimates." Journal of Neuroscience 10, no. 12 (December 1, 1990): 3823–36. http://dx.doi.org/10.1523/jneurosci.10-12-03823.1990.

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Strube, Michael J. "Some comments on the use of magnitude-of-effect estimates." Journal of Counseling Psychology 35, no. 3 (1988): 342–45. http://dx.doi.org/10.1037/0022-0167.35.3.342.

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Kamél, Lars. "The Uppsala Comet Magnitude Database." Symposium - International Astronomical Union 160 (1994): 495–96. http://dx.doi.org/10.1017/s0074180900046787.

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The second part of the Comet Light Curve Catalogue/Atlas (CLICC/A) has been made available by anonymous ftp. This database contains magnitude estimates of periodic comets, reduced to a geocentric distance of 1 AU and corrected for observational effects. The database is described in some detail.

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BRANDER, LUKE M., KATRIN REHDANZ, RICHARD S. J. TOL, and PIETER J. H. VAN BEUKERING. "THE ECONOMIC IMPACT OF OCEAN ACIDIFICATION ON CORAL REEFS." Climate Change Economics 03, no. 01 (February 2012): 1250002. http://dx.doi.org/10.1142/s2010007812500029.

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Because ocean acidification has only recently been recognized as a problem caused by CO2 emissions, impact studies are still rare and estimates of the economic impact are absent. This paper estimates the economic impact of ocean acidification on coral reefs which are generally considered to be economically as well as ecologically important ecosystems. First, we conduct an impact assessment in which atmospheric concentration of CO2 is linked to ocean acidity causing coral reef area loss. Next, a meta-analytic value transfer is applied to determine the economic value of coral reefs around the world. Finally, these two analyses are combined to estimate the economic impact of ocean acidification on coral reefs for the four IPCC marker scenarios. We find that the annual economic impact rapidly escalates over time, because the scenarios have rapid economic growth in the relevant countries and coral reefs are a luxury good. Nonetheless, the annual value in 2100 in still only a fraction of total income, one order of magnitude smaller than the previously estimated impact of climate change. Although the estimated impact is uncertain, the estimated confidence interval spans one order of magnitude only. Future research should seek to extend the estimates presented here to other impacts of ocean acidification and investigate the implications of our findings for climate policy.

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Leon, Evangelia, Sarah L. Gassman, and Pradeep Talwani. "Effect of Soil Aging on Assessing Magnitudes and Accelerations of Prehistoric Earthquakes." Earthquake Spectra 21, no. 3 (August 2005): 737–59. http://dx.doi.org/10.1193/1.1949223.

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Increase in strength due to aging of sands is reflected in higher blow counts and tip resistance values in penetration resistance measurements. This affects the magnitudes and peak ground acceleration estimates of prehistoric earthquakes obtained from an analysis of geotechnical observations at paleoliquefaction sites in the South Carolina Coastal Plain. In this study, corrections were made to account for the effects of soil aging, which were neglected in earlier estimates. The results show that when the effects of aging of soils on their geotechnical properties are incorporated, the resulting back-calculations reduced earlier magnitude estimates of prehistoric earthquakes by about 0.9 units. The peak ground acceleration estimates were reduced by about 15% for those earthquakes originally estimated at approximately 0.15 g. For those earthquakes whose original estimates were greater than 0.2 g, there was no noticeable change when a correction was made for the aging of soils.

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Schmid, Martin, Neil Burch, Marc Lanctot, Matej Moravcik, Rudolf Kadlec, and Michael Bowling. "Variance Reduction in Monte Carlo Counterfactual Regret Minimization (VR-MCCFR) for Extensive Form Games Using Baselines." Proceedings of the AAAI Conference on Artificial Intelligence 33 (July 17, 2019): 2157–64. http://dx.doi.org/10.1609/aaai.v33i01.33012157.

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Learning strategies for imperfect information games from samples of interaction is a challenging problem. A common method for this setting, Monte Carlo Counterfactual Regret Minimization (MCCFR), can have slow long-term convergence rates due to high variance. In this paper, we introduce a variance reduction technique (VR-MCCFR) that applies to any sampling variant of MCCFR. Using this technique, periteration estimated values and updates are reformulated as a function of sampled values and state-action baselines, similar to their use in policy gradient reinforcement learning. The new formulation allows estimates to be bootstrapped from other estimates within the same episode, propagating the benefits of baselines along the sampled trajectory; the estimates remain unbiased even when bootstrapping from other estimates. Finally, we show that given a perfect baseline, the variance of the value estimates can be reduced to zero. Experimental evaluation shows that VR-MCCFR brings an order of magnitude speedup, while the empirical variance decreases by three orders of magnitude. The decreased variance allows for the first time CFR+ to be used with sampling, increasing the speedup to two orders of magnitude.

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Claire Perry, H. K., Allison L. Bent, Daniel E. McNamara, Stephen Crane, and Michal Kolaj. "Earthquake Magnitude and Lg Q Variations between the Grenville and Northern Appalachian Geologic Provinces of Eastern Canada." Bulletin of the Seismological Society of America 110, no. 2 (February 4, 2020): 698–714. http://dx.doi.org/10.1785/0120190145.

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ABSTRACT This article assesses the ability of regionally specific, frequency-dependent crustal attenuation (1/Q) to reduce mean magnitude discrepancies between seismic stations in the northern Appalachian and Grenville provinces (NAP and GP) of Canada. LgQ(f) is an important parameter in ground-motion models used in probabilistic seismic hazard analysis. Discrepancies in regional magnitude estimates have long been noted to exist between stations in the two provinces for common event origins. Such discrepancies could arise from systematic site condition variations between the geologic provinces or from varying crustal attenuative properties. To evaluate the effect of frequency-dependent anelastic attenuation, LgQ(f) on estimated magnitudes, we analyze Lg amplitudes from >6000 waveforms recorded by Grenville and northern Appalachian receivers from 420 natural earthquakes of MN magnitude 3–5.6. Waveform analysis is strictly limited to analyst-reviewed, vertical-component waveforms in which Lg is clearly identified, ensuring that the datasets exhibit dominant, high-frequency energy in the Lg velocity window. LgQ(f) is found to be higher in the GP than in the northern Appalachians. In the Grenville, Q(f)=761(±145)f0.25(±0.014), and in the northern Appalachians, attenuation is higher: Q(f)=506(±172)f0.33(±0.310). Earthquake magnitude determined using the peak amplitude of the Lg phase (mbLg) for eastern Canada is corrected to incorporate the frequency-dependent, regionally specific LgQ(f) determined in this study. Using the new LgQ(f) values diminishes and nearly resolves magnitude discrepancies between the provinces. Correcting regional magnitude discrepancies between provinces is critical for reliable regional seismic hazard estimates because magnitude error in a particular region could lead to increased uncertainty in seismic hazard models.

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Smith, Rebecca A., and Christian D. Kummerow. "A Comparison of in Situ, Reanalysis, and Satellite Water Budgets over the Upper Colorado River Basin." Journal of Hydrometeorology 14, no. 3 (June 1, 2013): 888–905. http://dx.doi.org/10.1175/jhm-d-12-0119.1.

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Abstract Using in situ, reanalysis, and satellite-derived datasets, surface and atmospheric water budgets of the Upper Colorado River basin are analyzed. All datasets capture the seasonal cycle for each water budget component. For precipitation, all products capture the interannual variability, though reanalyses tend to overestimate in situ while satellite-derived precipitation underestimates. Most products capture the interannual variability of evapotranspiration (ET), though magnitudes differ among the products. Variability and magnitude among storage volume change products widely vary. With regards to the surface water budget, the strongest connections exist among precipitation, ET, and soil moisture, while snow water equivalent (SWE) is best correlated with runoff. Using in situ precipitation estimates, the Max Planck Institute (MPI) ET estimates, and accumulated runoff, changes in storage are calculated and compare well with estimated changes in storage calculated using SWE, reservoir, and the Climate Prediction Center’s soil moisture. Using in situ precipitation estimates, MPI ET estimates, and atmospheric divergence estimates from the European Centre for Medium-Range Weather Forecasts Interim Re-Analysis (ERA-Interim) results in a long-term atmospheric storage change estimate of −73 mm. Long-term surface storage estimates combined with long-term runoff come close to balancing with long-term atmospheric convergence from ERA-Interim. Increasing the MPI ET by 5% leads to a better balance between surface storage changes, runoff, and atmospheric convergence. It also brings long-term atmospheric storage changes to a better balance at +13 mm.

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Jónasson, Kristján, Bjarni Bessason, Ásdís Helgadóttir, Páll Einarsson, Gunnar B. Guðmundsson, Bryndís Brandsdóttir, Kristín S. Vogfjörd, and Kristín Jónsdóttir. "A harmonised instrumental earthquake catalogue for Iceland and the northern Mid-Atlantic Ridge." Natural Hazards and Earth System Sciences 21, no. 7 (July 21, 2021): 2197–214. http://dx.doi.org/10.5194/nhess-21-2197-2021.

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Abstract. A comprehensive catalogue of historical earthquakes, with accurate epicentres and harmonised magnitudes is a crucial resource for seismic hazard mapping. Here we update and combine catalogues from several sources to compile a catalogue of earthquakes in and near Iceland, in the years 1900–2019. In particular the epicentres are based on local information, whereas the magnitudes are based on teleseismic observations, primarily from international online catalogues. The most reliable epicentre information comes from the catalogue of the Icelandic Meteorological Office, but this is complemented with information from several technical reports, scientific publications, and newspaper articles. The catalogue contains 1281 moment magnitude (Mw) ≥4 events, and the estimated completeness magnitude is Mw 5.5 in the first years, going down to Mw 4.5 for recent years. The largest magnitude is Mw 7.0. Such merging of local data and teleseismic catalogues has not been done before for Icelandic earthquakes, and the result is an earthquake map with much more accurate locations than earlier maps. The catalogue also lists 5640 additional earthquakes on the Mid-Atlantic Ridge, north of 43∘, with both epicentres and magnitudes determined teleseismically. When moment magnitudes are not available, proxy Mw values are computed using χ2 regression, normally on the surface-wave magnitude but exceptionally on the body-wave magnitude. Magnitudes of Mw≥4.5 have associated uncertainty estimates. The actual combined seismic moment released in the Icelandic earthquakes is found to be consistent with the moment estimated using a simple plate motion model, indicating that the seismic activity of the catalogue period might be typical of any 120-year time span. The catalogue is named ICEL-NMAR, and it is available online at http://data.mendeley.com (last access: 19 July 2021).

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Abercrombie, Rachel E. "Regional bias in estimates of earthquake MS due to surface-wave path effects." Bulletin of the Seismological Society of America 84, no. 2 (April 1, 1994): 377–82. http://dx.doi.org/10.1785/bssa0840020377.

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Abstract Continental earthquakes have long been known to have anomalously high surface-wave magnitudes relative to their seismic moments. A recent global study of shallow earthquakes by Ekström and Dziewonski (1988) confirmed this and found other regional, systematic anomalies in the MS-M0 relationship. It is important to determine the source of these anomalies in order to understand the controls on earthquake-source radiation and to obtain accurate estimates of historical seismic strain rates. In this study the magnitudes of 82 earthquakes from eight different tectonic regions are recalculated using a simple surface-wave path correction to determine whether path effects are responsible for the observed anomalies. The magnitudes of continental earthquakes are reduced by an average of 0.2 magnitude units, an improvement in fit to the global average significant at the 98% level. Surface-wave path effects are clearly responsible for the high MS observed in continental areas. There is a small decrease in scatter in the other areas, but lateral refraction of the surface waves at plate boundaries prevents the simple correction from having a significant effect. There is no evidence in the observed anomalies, however, for any dependence of earthquake-source type on tectonic setting. It is clear that to obtain reliable, unbiased estimates of regional seismic strain rate and hazard, a local moment-magnitude relationship should be preferred to a global one.

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McKelvie, Stuart J. "Factors Affecting Subjective Estimates of Magnitude: When is 9 > 221?" Perceptual and Motor Skills 93, no. 2 (October 2001): 432–34. http://dx.doi.org/10.2466/pms.2001.93.2.432.

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McKELVIE, STUART J. "FACTORS AFFECTING SUBJECTIVE ESTIMATES OF MAGNITUDE: WHEN IS 9 > 221?" Perceptual and Motor Skills 93, no. 6 (2001): 432. http://dx.doi.org/10.2466/pms.93.6.432-434.

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Boyd, Robert W. "Erratum Order-of-magnitude estimates of the non-linear optical susceptibility." Journal of Modern Optics 47, no. 6 (May 15, 2000): 1147. http://dx.doi.org/10.1080/095003400147728.

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Predebon, John. "The Influence of Object Familiarity on Magnitude Estimates of Apparent Size." Perception 21, no. 1 (February 1992): 77–90. http://dx.doi.org/10.1068/p210077.

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Three magnitude-estimation experiments were used to determine the exponents of the power function relating size judgments and physical size for two-dimensional familiar and unfamiliar stimuli. The exponent of the power function was used to index the effect of familiar size on perceived size under a variety of conditions, from full-cue to reduced-cue viewing conditions. Although the value of the exponents varied across the three experiments, within each experiment the exponent of the familiar stimulus was not significantly different from that of the unfamiliar stimulus, indicating that familiar size does not influence the rate of growth of perceived size. The results of a fourth experiment excluded a possible explanation of the findings of experiments 1–3 in terms of subjects responding to relative angular size as a consequence of the successive presentation of the different-sized representations of the familiar stimulus. Taken together, the present findings are consistent with the hypothesis that the influence of familiar size on estimates of size mainly reflects the intrusion of nonperceptual processes in spatial responses.

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Wyszkowska, P., and R. Duchnowski. "Systematic bias of selected estimates applied in vertical displacement analysis." Journal of Geodetic Science 10, no. 1 (June 2, 2020): 41–47. http://dx.doi.org/10.1515/jogs-2020-0103.

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AbstractIn surveying problems we almost always use unbiased estimators; however, even unbiased estimator might yield biased assessments, which is due to data. In statistics one distinguishes several types of such biases, for example, sampling, systemic or response biases. Considering surveying observation sets, bias from data might result from systematic or gross errors of measurements. If nonrandom errors in an observation set are known, then bias can easily be determined for linear estimates (e.g., least squares estimates). In the case of non-linear estimators, it is not so simple. In this paper we are focused on a vertical displacement analysis and we consider traditional least squares estimate, two Msplitestimates and two basic robust estimates, namely M-estimate, R-estimate. The main aim of the paper is to assess estimate biases empirically by applying Monte Carlo method. The smallest biases are obtained for M- and R-estimates, especially for a high magnitude of a gross error. On the other hand, there are several cases when Msplitestimates are the best. Such results are acquired when the magnitude of a gross error is moderate or small. The outcomes confirm that bias of Msplitestimates might vary for different point displacements.

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Wu, Shen-Chyun, C. Allin Cornell, and Steven R. Winterstein. "A hybrid recurrence model and its implication on seismic hazard results." Bulletin of the Seismological Society of America 85, no. 1 (February 1, 1995): 1–16. http://dx.doi.org/10.1785/bssa0850010001.

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Abstract To account for the effects of the characteristic earthquakes on an individual fault (segment), a renewal hybrid model is proposed for seismic hazard analysis and studied in depth. This model incorporates a renewal-time, characteristic-magnitude model for larger earthquakes with the conventional exponential-time, exponential-magnitude model for smaller earthquakes. Properties of important temporal and magnitude parameters are studied. The exact and the approximate (“first-event”) hazards estimated by this model are discussed. The approximate results are found sufficiently accurate for most engineering applications. These approximations can be obtained by making minor modifications to existing hazard analysis programs designed for traditional Poisson models. Hazard estimates of this model and other more complicated hybrid models, e.g., time- and slip-predictable models, are compared. For reasonable parameter values, the characteristic events are found to be the major contributor to seismic hazards in most cases, unless the source-site distance is very small. This effect is even stronger with a large elapsed time in a nonmemoryless interarrival time distribution. Based on previous findings of small values of the coefficients of variation in time and low correlations between the interarrival times and magnitudes among characteristic earthquakes, the proposed renewal hybrid model will produce hazard estimates close to those of more complicated non-Poissonian models.

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Hirose, Fuyuki, Kenji Maeda, and Yasuhiro Yoshida. "Maximum magnitude of subduction earthquakes along the Japan-Kuril-Kamchatka trench estimated from seismic moment conservation." Geophysical Journal International 219, no. 3 (August 23, 2019): 1590–612. http://dx.doi.org/10.1093/gji/ggz381.

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SUMMARY We estimated the maximum magnitude of earthquakes in the Japan-Kuril-Kamchatka trench subduction zone with a method based on the conservation of seismic moment and the record of interplate seismicity from 1977 to 2017. The key point of this method is to base calculations on the tectonic moment rate instead of the total seismic moment rate. We modeled a seismic-moment-frequency distribution for the Japan-Kuril-Kamchatka trench on the basis of the truncated Gutenberg–Richter (G–R) law, the formula published by Utsu in 1974, the gamma distribution, and the tapered G–R law. We estimated the maximum magnitude along the Japan-Kuril-Kamchatka trench as ∼10 under the truncated G–R law and ∼11 under Utsu's formula, although the latter may be an overestimate. Therefore, the 2011 Tohoku earthquake, of moment magnitude 9.2, may not be the largest possible event in this area. The recurrence interval for magnitude 10 events based on the truncated G–R law is 4000 yr. Although these two models perform equally well in terms of Akaike Information Criterion, the range of the 95 per cent confidence level is consistently narrower for the truncated G–R law than for Utsu's formula. The estimated maximum magnitude depends not only on the model used, but also on the parameters that constitute the tectonic moment. It is essential to accumulate more seismic data and achieve more precise estimates of tectonic moment to improve estimates of maximum magnitude.

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Carvalho, Ludmilla A. Marques de, Guilherme F. de Moura, Dheynne A. Vieira, Naudin A. Hurtado-Lugo, Rusbel R. Aspilcueta-Borquis, Ana P. C. Gomide, Humberto Tonhati, Henrique N. de Oliveira, and Francisco R. de Araujo-Neto. "Short communication: Genetic analysis of lactation curves in buffaloes, using Wood’s model." Spanish Journal of Agricultural Research 18, no. 3 (December 29, 2020): e04SC01. http://dx.doi.org/10.5424/sjar/2020183-15461.

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Aim of study: To estimate the heritability and genetic correlations for lactation curve traits in buffaloes.Area of study: The buffalo cows were raised on properties located in the states of São Paulo, Ceará and Rio Grande do Norte, Brazil.Material and methods: The individual parameters of Wood’s model ( , , and ) were obtained using a non-linear mixed model. Peak yield (PY), peak time (PT) and lactation persistency (LP) were also calculated. These individual parameters were employed in multi-trait analysis with the milk yield (MY) using Bayesian inference.Main results: The heritability estimates were of low to moderate magnitudes, with values ranging from 0.156 ( ) to 0.299 (PY). The estimates for genetic correlation between the Wood’s parameters and MY were of low to high magnitude and ranged from -0.533 ( and MY) to 0.983 (PY and MY).Research highlights: The heritability estimates obtained indicate that the traits studied can be used in animal breeding programs.

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Crosbie, R. S., I. D. Jolly, F. W. Leaney, and C. Petheram. "Can the dataset of field based recharge estimates in Australia be used to predict recharge in data-poor areas?" Hydrology and Earth System Sciences 14, no. 10 (October 25, 2010): 2023–38. http://dx.doi.org/10.5194/hess-14-2023-2010.

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Abstract. Effective management of water resources requires that all elements of the water balance be estimated. Groundwater recharge measurements are difficult, time consuming and expensive. In some cases a field study cannot be justified and simple empirical relationships are used to estimate recharge, and often the value chosen is simply a percentage of rainfall. This paper aims to use a database of 4386 field based estimates of recharge from 172 studies in Australia to produce simple empirical relationships that relate recharge to nationally available datasets and hence can be used to estimate recharge in data-poor areas in a scientifically defensible way. It was found that the vegetation and soil type were critical determinants in forming relationships between average annual rainfall and average annual recharge. Climate zones and surface geology (lithology) were not found to be significant determinants in the relationship between rainfall and recharge. The method used to estimate recharge had an impact upon the magnitude of the recharge estimates due to the spatial and temporal scales over which the different methods estimate recharge. Relationships have been developed here between average annual rainfall and average annual recharge for combinations of soil and vegetation type that can be used with only nationally available datasets to provide a recharge estimate. These relationships can explain 60% of the variance in recharge measurements across Australia. The uncertainty in the recharge estimated using these relationships is generally greater than an order of magnitude. This means that if these relationships are used to help determine water allocations, then the precautionary principle should limit allocations to less than about 5% of the estimated recharge. If allocations are greater than this, a more detailed site specific study is warranted.

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Miralles, D. G., R. A. M. De Jeu, J. H. Gash, T. R. H. Holmes, and A. J. Dolman. "Magnitude and variability of land evaporation and its components at the global scale." Hydrology and Earth System Sciences 15, no. 3 (March 17, 2011): 967–81. http://dx.doi.org/10.5194/hess-15-967-2011.

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Abstract. A process-based methodology is applied to estimate land-surface evaporation from multi-satellite information. GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology) combines a wide range of remotely-sensed observations to derive daily actual evaporation and its different components. Soil water stress conditions are defined from a root-zone profile of soil moisture and used to estimate transpiration based on a Priestley and Taylor equation. The methodology also derives evaporationfrom bare soil and snow sublimation. Tall vegetation rainfall interception is independently estimated by means of the Gash analytical model. Here, GLEAM is applied daily, at global scale and a quarter degree resolution. Triple collocation is used to calculate the error structure of the evaporation estimates and test the relative merits of two different precipitation inputs. The spatial distribution of evaporation – and its different components – is analysed to understand the relative importance of each component over different ecosystems. Annual land evaporation is estimated as 67.9 × 103 km3, 80% corresponding to transpiration, 11% to interception loss, 7% to bare soil evaporation and 2% snow sublimation. Results show that rainfall interception plays an important role in the partition of precipitation into evaporation and water available for runoff at a continental scale. This study gives insights into the relative importance of precipitation and net radiation in driving evaporation, and how the seasonal influence of these controls varies over different regions. Precipitation is recognised as an important factor driving evaporation, not only in areas that have limited soil water availability, but also in areas of high rainfall interception and low available energy.

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Nihous, Gérard C. "An Order-of-Magnitude Estimate of Ocean Thermal Energy Conversion Resources." Journal of Energy Resources Technology 127, no. 4 (April 5, 2005): 328–33. http://dx.doi.org/10.1115/1.1949624.

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Worldwide power resources that could be extracted from the steady-state operation of ocean thermal energy conversion (OTEC) plants are estimated using a simple model. This order-of-magnitude analysis indicates that about 3×109kW (3 TW) may be available, at most. This value is much smaller than estimates currently suggested in the technical literature. It reflects the scale of the perturbation caused by massive OTEC seawater flow rates on the thermal structure of the ocean. Not surprisingly, maximum OTEC power nearly corresponds to deep cold seawater flow rates of the order of the average abyssal upwelling representative of the global thermohaline circulation.

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Herold, C., and F. Mouton. "Global flood hazard mapping using statistical peak flow estimates." Hydrology and Earth System Sciences Discussions 8, no. 1 (January 18, 2011): 305–63. http://dx.doi.org/10.5194/hessd-8-305-2011.

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Abstract. Our aim is to produce a world map of flooded areas for a 100 year return period, using a method based on large rivers peak flow estimates derived from mean monthly discharge time-series. Therefore, the map is supposed to represent flooding that affects large river floodplains, but not events triggered by specific conditions like coastal or flash flooding for instance. We first generate for each basin a set of hydromorphometric, land cover and climatic variables. In case of an available discharge record station at the basin outlet, we base the hundred year peak flow estimate on the corresponding time-series. Peak flow magnitude for basin outlets without gauging stations is estimated by statistical means, performing several regressions on the basin variables. These peak flow estimates enable the computation of corresponding flooded areas using hydrologic GIS processing on digital elevation model.

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Münchmeyer, Jannes, Dino Bindi, Christian Sippl, Ulf Leser, and Frederik Tilmann. "Low uncertainty multifeature magnitude estimation with 3-D corrections and boosting tree regression: application to North Chile." Geophysical Journal International 220, no. 1 (September 17, 2019): 142–59. http://dx.doi.org/10.1093/gji/ggz416.

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SUMMARY Magnitude estimation is a central task in seismology needed for a wide spectrum of applications ranging from seismicity analysis to rapid assessment of earthquakes. However, magnitude estimates at individual stations show significant variability, mostly due to propagation effects, radiation pattern and ambient noise. To obtain reliable and precise magnitude estimates, measurements from multiple stations are therefore usually averaged. This strategy requires good data availability, which is not always given, for example for near real time applications or for small events. We developed a method to achieve precise magnitude estimations even in the presence of only few stations. We achieve this by reducing the variability between single station estimates through a combination of optimization and machine learning techniques on a large catalogue. We evaluate our method on the large scale IPOC catalogue with >100 000 events, covering seismicity in the northern Chile subduction zone between 2007 and 2014. Our aim is to create a method that provides low uncertainty magnitude estimates based on physically meaningful features. Therefore we combine physics based correction functions with boosting tree regression. In a first step, we extract 110 features from each waveform, including displacement, velocity, acceleration and cumulative energy features. We correct those features for source, station and path effects by imposing a linear relation between magnitude and the logarithm of the features. For the correction terms, we define a non-parametric correction function dependent on epicentral distance and event depth and a station specific, adaptive 3-D source and path correction function. In a final step, we use boosting tree regression to further reduce interstation variance by combining multiple features. Compared to a standard, non-parametric, 1-D correction function, our method reduces the standard deviation of single station estimates by up to $57\, {\rm per\, cent}$, of which $17\, {\rm per\, cent}$ can be attributed to the improved correction functions, while boosting tree regression gives a further reduction of $40\, {\rm per\, cent}$. We analyse the resulting magnitude estimates regarding their residuals and relation to each other. The definition of a physics-based correction function enables us to inspect the path corrections and compare them to structural features. By analysing feature importance, we show that envelope and P wave derived features are key parameters for reducing uncertainties. Nonetheless the variety of features is essential for the effectiveness of the boosting tree regression. To further elucidate the information extractable from a single station trace, we train another boosting tree on the uncorrected features. This regression yields magnitude estimates with uncertainties similar to the single features after correction, but without using the earthquake location as required for applying the correction terms. Finally, we use our results to provide high precision magnitudes and their uncertainties for the IPOC catalogue.

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Journal articles on the topic 'Magnitude estimates'

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