scholarly journals Local magnitude, duration magnitude and seismic moment of Dahshour 1992 earthquakes

2009 ◽  
Vol 43 (1) ◽  
Author(s):  
M. M. Dessokey ◽  
H. M. Hussein ◽  
E. M. Abdelrahman ◽  
M. F. Abdelwahed
Keyword(s):  
Seismic Moment ◽  
Local Magnitude ◽  
Duration Magnitude

Seismic moments, local magnitudes, and coda-duration magnitudes for earthquakes in central California

1984 ◽  
Vol 74 (2) ◽  
pp. 439-458 ◽  
Author(s):  
William H. Bakun
Keyword(s):  
Seismic Moment ◽  
San Andreas Fault ◽  
Seismic Network ◽  
San Juan ◽  
Local Magnitude ◽  
Central California ◽  
San Andreas ◽  
Duration Magnitude ◽  
San Juan Bautista ◽  
The U.S

Abstract Onscale seismograms recorded at stations in the U.S. Geological Survey's (USGS) central California seismic network (CALNET) have been used to estimate the seismic moment M0 and local magnitude ML for earthquakes of 1 ≦ ML ≦ 4 located on the San Juan Bautista and Parkfield sections of the San Andreas fault, the Coyote Lake section of the Calaveras fault, the Sargent fault, and near Livermore. These data, together with M0 and ML estimates for 4 ≦ ML ≦ 6 earthquakes in these areas, cannot be fit with a single linear log M0-versus-ML relation. Rather, the data are consistent with log M0 = 1.5 ML + 16 for 3 ≲ ML ≲ 6, with log M0 = 1.2 ML + 17 for 1 1/2 ≲ ML ≲ 3 1/2 and with a slope of ⅔ to 1 fro 1/2 ≲ ML ≲ 1 1/2. Whereas USGS coda duration magnitude MD is consistent with ML for 1 1/2 ≲ ML ≲ 3¼, MD is larger than ML at ML ≲ 1 1/2 and smaller than ML at ML ≳ 3¼. Log M0 can be estimated to a precision of 0.2 for 1 ≦ MD ≦ 3 1/2 earthquakes in central California by applying log M0 = 1.2 MD + 17 to the MD that have been routinely published by the USGS.

The use of duration as a measure of seismic moment and magnitude

1975 ◽  
Vol 65 (4) ◽  
pp. 899-913
Author(s):  
Robert B. Herrmann
Keyword(s):  
United States ◽  
Linear Relationship ◽  
Linear Dependence ◽  
Seismic Moment ◽  
Instrumental Response ◽  
Limited Range ◽  
Corner Frequency ◽  
Source Spectrum ◽  
Duration Magnitude ◽  
Central United States

Abstract The observed relationship between magnitude and duration is shown to be a result of the particular shape of the signal coda as a function of time. If the envelope of the coda follows a t−q relationship with increasing time, then the magnitude, mτ, based on a duration τ is consequently of the form m τ = q log ⁡ 10 τ + r . A study of the duration-magnitude and duration-moment relationships for a set of central United States earthquakes indicates that the linear relationship between mτ and log10τ is valid only over a limited range. The departure from the simple linear dependence is explained in terms of instrumental response and the shift of the source-spectrum corner frequency with increasing event size.

scholarly journals Analysis of strong-motion data of the 1990 Eastern Sicily earthquake

1995 ◽  
Vol 38 (2) ◽  
Author(s):  
M. Di Bona ◽  
M. Cocco ◽  
A. Rovelli ◽  
R. Berardi ◽  
E. Boschi
Keyword(s):  
Frequency Band ◽  
Stress Drop ◽  
Seismic Moment ◽  
Ground Motions ◽  
Broad Band ◽  
Strong Motion ◽  
Moment Magnitude ◽  
Corner Frequency ◽  
Local Magnitude ◽  
The Moment

The strong motion accelerograms recorded during the 1990 Eastern Sicily earthquake have been analyzed to investigate source and attenuation parameters. Peak ground motions (peak acceleration, velocity and displacement) overestimate the values predicted by the empirical scaling law proposed for other Italian earthquakes, suggesting that local site response and propagation path effects play an important role in interpreting the observed time histories. The local magnitude, computed from the strong motion accelerograms by synthesizing the Wood-Anderson response, is ML = 5.9, that is sensibly larger than the local magnitude estimated at regional distances from broad-band seismograms (ML = 5.4). The standard omega-square source spectral model seems to be inadequate to describe the observed spectra over the entire frequency band from 0.2 to 20 Hz. The seismic moment estimated from the strong motion accelerogram recorded at the closest rock site (Sortino) is Mo = 0.8 x 1024 dyne.cm, that is roughly 4.5 times lower than the value estimated at regional distances (Mo = 3.7 x 1024 dyne.cm) from broad-band seismograms. The corner frequency estimated from the accelera- tion spectra i.5 J; = 1.3 Hz, that is close to the inverse of the dUl.ation of displacement pulses at the two closest recording sites. This value of corner tì.equency and the two values of seismic moment yield a Brune stress drop larger than 500 bars. However, a corner frequency value off; = 0.6 Hz and the seismic moment resulting from regional data allows the acceleration spectra to be reproduced on the entire available frequency band yielding to a Brune stress drop of 210 bars. The ambiguity on the corner frequency value associated to this earthquake is due to the limited frequency bandwidth available on the strong motion recordil1gs. Assuming the seismic moment estimated at regional distances from broad-band data, the moment magnitude for this earthquake is 5.7. The higher local magnitude (5.9) compared with the moment magnitude (5.7) is due to the weak regional attenuation. Beside this, site amplifications due to surface geology have produced the highest peak ground motions among those observed at the strong motion sites.

Local magnitudes, seismic moments, and coda durations for earthquakes near Oroville, California

1977 ◽  
Vol 67 (3) ◽  
pp. 615-629 ◽  
Author(s):  
W. H. Bakun ◽  
A. G. Lindh
Keyword(s):  
Seismic Moment ◽  
Vertical Component ◽  
Local Magnitude ◽  
Short Period ◽  
Rms Error ◽  
Point Of Intersection ◽  
Epicentral Region

abstract Seismic moments Mo and local magnitudes ML for earthquakes near Oroville, California imply the linear log seismic moment-local magnitude relation log ⁡ 10 ( M o ) = ( 1.21 ± 0.03 ) M L + ( 17.02 ± 0.07 ) for 17 < log 10 M o < 25. Coda durations τ for short-period, vertical-component seismographs located in the epicentral region are related to local magnitude using two linear log τ-ML segments with point of intersection at ML ≂ 1.5. The rms error is 0.1 to 0.2 units of magnitude. A relation of the form log Mo = a1 + a3 (log τ)2 is sufficient (in the sense that rms error in log10Mo is 0.2 to 0.3 units) to relate τ and Mo for 18 ≦ log10Mo < 22. Coefficients for the above τ-ML and τ-Mo relationships are established for three seismographs of differing response

Simplified estimation of seismic moment from seismograms

1983 ◽  
Vol 73 (3) ◽  
pp. 735-748
Author(s):  
Bruce A. Bolt ◽  
Miguel Herraiz
Keyword(s):  
Spectral Analysis ◽  
Least Squares ◽  
Empirical Result ◽  
Seismic Moment ◽  
Epicentral Distance ◽  
Moment Magnitude ◽  
Local Magnitude ◽  
Logarithmic Term ◽  
Central California ◽  
Maximum Peak

abstract This study proposes a method to estimate the seismic moment of regional and local earthquakes based on simple measurements made directly on Wood-Anderson seismograms. The method parallels the routine estimation of local magnitude in observatory work. The relation used is log M o = a + b log ( C × D × Δ p ) where C is the maximum peak-to-peak amplitude read on a Wood-Anderson seismogram, D is the duration between the S arrival and the onset with amplitude C/d, Δ is epicentral distance, and a, b, p, and d are constants. The form of the logarithmic term is suggested by the analytical expression for moment (Keilis-Borok, 1960). Least-squares fits were made to data from 73 Wood-Anderson records of 16 central California earthquakes with seismic moments already evaluated independently from spectral analysis or broadband displacement records. The values p = 1, d, = 3 proved appropriate and subsequent regression yielded log M o = ( 16.74 ± 0.20 ) + ( 1.22 ± 0.14 ) log ( C × D × Δ ) where Mo is dyne-cm, C in millimeters, D in seconds, and Δ in kilometers. The corresponding moment-magnitude relation is log M o = ( 17.92 ± 1.02 ) + ( 1.11 ± 0.15 ) M L , for 3 ≦ ML ≦ 6.2. The latter fit is close to an earlier empirical result (Johnson and McEvilly, 1974) for central California based on fewer cases and a different range of magnitude (2.4 ≦ ML ≦ 5.1).

scholarly journals Discrimination of Small Earthquakes and Buried Single-Fired Chemical Explosions at Local Distances (<150  km) in the Western United States from Comparison of Local Magnitude (ML) and Coda Duration Magnitude (MC)

2020 ◽  
Author(s):  
Keith D. Koper ◽  
Monique M. Holt ◽  
Jonathan R. Voyles ◽  
Relu Burlacu ◽  
Moira L. Pyle ◽  
...  
Keyword(s):  
United States ◽  
High Frequency ◽  
Characteristic Curve ◽  
Moment Tensor ◽  
Western United States ◽  
Local Magnitude ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Duration Magnitude ◽  
Chemical Explosions

ABSTRACT Seismologists distinguish underground nuclear explosions from more commonly occurring earthquakes using moment tensor inversion, high-frequency P/S amplitude ratios, mb:Ms comparisons, and P-pP differential travel times. These methods are generally successful for large seismic events (M&gt;3–4) well recorded at regional-to-teleseismic distances (&gt;150  km); however, it is unclear whether they can be modified to work for small events (M&lt;3) well recorded only at local distances (&lt;150  km). Here, we evaluate a recently proposed, local-distance seismic source discriminant—the difference between local magnitude (ML) and coda duration magnitude (MC)—using seismograms of earthquakes and buried, single-fired chemical explosions recorded in three regions of the western United States. The quantity ML–MC was previously found to be sensitive to source depth, effectively discriminating mine blasts, induced earthquakes, and very shallow tectonic earthquakes from deeper crustal earthquakes. In this study, we report the first evaluation of ML–MC as a depth discriminant using data from buried, single-fired explosions that, unlike the seismic sources studied earlier, are good analogs for underground nuclear explosions. We find that even when using generic, uncalibrated methods of assigning magnitudes, ML–MC separates single-fired explosions and earthquakes. The area under the receiver operating characteristic curve is 0.92 for 19 explosions and 14 earthquakes in Washington, 0.90 for 22 explosions and 90 earthquakes in Wyoming, and 0.99 for three explosions and 149 earthquakes in Nevada. ML:MC comparisons have the potential to enhance discrimination based on high-frequency P/S amplitudes ratios—which perform less well at local than regional distances—because the two metrics have complementary sensitivities.

scholarly journals A new MD-ML relationship for Mt. Etna earthquakes (Italy)

2016 ◽  
Vol 58 (6) ◽  
Author(s):  
Tiziana Tuvè ◽  
Salvatore D'Amico ◽  
Elisabetta Giampiccolo
Keyword(s):  
Basic Requirement ◽  
Local Magnitude ◽  
Orthogonal Regression ◽  
Seismic Catalogue ◽  
Duration Magnitude ◽  
Dependent Variables ◽  
Mt Etna ◽  
Hazard Estimation ◽  
The Relationship ◽  
Seismic Hazard Estimation

<p class="Testoformula">A homogenous database of magnitude observations is a basic requirement for seismic hazard estimation and other seismic studies. Unfortunately, the magnitude reported in the seismic catalogue of Mt. Etna is not homogenous.  Until 2005 only the duration magnitude (M<sub>D</sub>) is available, though since then the more stable local magnitude (M<sub>L</sub>) has also been calculated. To overcome this limitation, earthquake data recorded at Mt. Etna during the period 2005 – 2014 were used to derive a new relationship between local and duration magnitude, by applying the General Orthogonal Regression (GOR) which is an alternative to least squares when the ratio between errors on the independent and the dependent variables can be estimated. The relationship obtained is:</p><p class="Testoformula">     M<sub>L</sub> = 1.164 (± 0.011) * M<sub>D</sub> - 0.337 (± 0.020)                                          </p><p> The new relationship allows to back-extend the local magnitude dataset to cover a period of about 15 years.</p>

Numerosity, area surface, duration magnitude processing: No evidence for a shared mechanism in children

2011 ◽  
Author(s):  
C. Mussolin ◽  
D. Hoffmann ◽  
C. Schiltz ◽  
J. Leybaert ◽  
A. Content
Keyword(s):  
Magnitude Processing ◽  
Duration Magnitude
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