Regional Magnitude Scaling, Transportability, and Ms:mb Discrimination at Small Magnitudes

Patton, Howard J.

doi:10.1007/978-3-0348-8310-8_4

Cited by 4 publications

(4 citation statements)

References 68 publications

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“…In our analysis we assume that the source spectra obtained with regional and teleseismic data are equal. Based on m b -M w and m b (Lg)-M w scaling and the saturation of m b but not m b (Lg) (Patton, 2001), it may be argued that the apparent source spectra retrieved from teleseismic P waves and regional S waves differ around 1 Hz. The difference in the scaling and the saturation of m b may also be attributable to the fact that m b is determined from the amplitude of first few cycles of teleseismic P Table 2.…”

Section: Discussionmentioning

confidence: 99%

Reconciling Teleseismic and Regional Estimates of Seismic Energy

Pérez‐Campos¹

2003

Bulletin of the Seismological Society of America

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Estimates of the radiated seismic energy based on teleseismic and regional data often differ by up to an order of magnitude, with a tendency for regional estimates to be larger than teleseismic estimates for the same event. In this study we compare the velocity spectrum determined from teleseismic data after correction for radiation pattern and propagation effects, with the velocity spectrum determined from regional data, after the corresponding corrections, for nine earthquakes in the Middle America subduction zone of Mexico. This comparison of the corrected spectra is used to identify and reduce the sources of the regional versus teleseismic energy discrepancy, which is about an order of magnitude for these events. We find that the teleseismic attenuation operator needs to be calibrated. In our case, for the tectonic environment of the Mexican subduction zone, we need a teleseismic attenuation operator that is stronger at high frequencies than the global average. A larger factor, however, is the correction needed to account for site amplification. This correction has an impact on both regional and teleseismic data, but it has a larger influence on the regional estimates because the angle of incidence for teleseismic waves is steep and the stations are located on more competent rock. By modifying the teleseismic attenuation operator and applying site corrections based on a generic site model, we essentially eliminate the order-of-magnitude discrepancy between teleseismic and regional estimates of the radiated seismic energy for these events.

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Section: Discussionmentioning

confidence: 99%

Reconciling Teleseismic and Regional Estimates of Seismic Energy

Pérez‐Campos¹

2003

Bulletin of the Seismological Society of America

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“…We veri®ed that the small m bLg measurements are reasonable by using them to estimate yield. Extrapolation based on the data PATTON (2000) used to obtain his uni®ed moment-magnitude (M w ) ) m bLg model and application of the M w -moment (M 0 ) scale of HANKS and KANAMORI (1979) lead to a moment estimate of 7.3´10 11 to 1.9´10 12 N-m for the 50-m shot. The range re¯ects the one-sigma prediction error from the M w ) m bLg regression.…”

Section: Datamentioning

confidence: 99%

Precise Relative Location of 25-ton Chemical Explosions at Balapan Using IMS Stations

Phillips¹,

Hartse²,

Steck³

2001

Pure appl. geophys.

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Ð We test how well low-magnitude (m bLg 1.8 to 2.6), 25-ton chemical explosions at Balapan, Kazakhstan, can be located using IMS stations and standard earth models, relying on precisely determined relative arrival times of nearly similar, regional and teleseismic waveforms. Three 1997 Balapan explosions were recorded by a number of currently reporting and surrogate IMS stations. Three regional stations and two teleseismic arrays yielded consistent waveforms appropriate for relative picking. Master-event locations based on the AK135 model and ground-truth information from the ®rst, shallowest and bestrecorded explosion, fell under 1 km from known locations, for depths constrained to that of the master event. The resulting 90% con®dence ellipses covered 12±13 km 2 and contained the true locations; however, results for depth constrained to true depth were slightly less satisfactory. From predictions based on ground truth, we found a P g -coda phase at Makanchi, Kazakhstan to be misidenti®ed and poorly modeled. After accounting for this, 90% ellipses shrank to 2±3 km 2 and true-depth mislocation vectors became more consistent with con®dence-ellipse orientations. These results suggest that a high level of precision could be provided by a tripartite array of calibration shots in cases where models are poorly known. We hope that the successful relocation of these small Balapan shots will support the role of calibration explosions in veri®cation monitoring and special event studies, including on-site inspection.

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“…However, the application conditions for m b ðLgÞ scaling in the continental margins were rarely investigated. Further, the potential underestimation with m b ðLgÞ scaling for events around continental margins is poorly known despite various studies on the transportability of m b ðLgÞ (e.g., PRIESTLEY and PATTON, 1997;PATTON, 2001).…”

Section: Introductionmentioning

confidence: 99%

Lg Body-Wave Magnitude Scaling for the Continental Margin around Korea and Japan

Hong

2011

Pure Appl. Geophys.

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Regional body-wave magnitude scalings are essential for quantification of small and moderate-size earthquakes that are observed only up to regional distances. Crustally-guided shear waves, Lg, develop stably at regional distances in continental crusts and are minimally influenced by the source radiation patterns. Lg body-wave magnitude scalings, m b ðLgÞ; are widely used for assessment of sizes of regional crustal events. The m b ðLgÞ scaling has rarely been tested in continental margins where Lg waves are significantly attenuated due to abrupt lateral variation of crustal structures. We test the applicability of m b ðLgÞ scaling to the eastern margin of the Eurasian plate around the Korean Peninsula and Japanese islands. Both third-peak and root-mean-square (rms) amplitudes of Lg vary significantly according to the crustal structures along raypaths, causing apparent underestimation of m b ðLgÞ: Implementation of raypath-dependent quality factors (Q) allows accurate estimation of m b ðLgÞ; retaining the transportability of m b ðLgÞ in the continental margin around Korea and Japan. The calibration constants for an rms-amplitude-based m b ðLgÞ scaling are not determined to vary by region in the continental margin due to complicated crustal structures. The calibration constants are determined to be distance-dependent. Both the third-peak-amplitude-based and rms-amplitude-based m b ðLgÞ scalings yield accurate magnitude estimates when raypath-dependent quality factors are implemented.

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Regional Magnitude Scaling, Transportability, and Ms:mb Discrimination at Small Magnitudes

Cited by 4 publications

References 68 publications

Reconciling Teleseismic and Regional Estimates of Seismic Energy

Reconciling Teleseismic and Regional Estimates of Seismic Energy

Precise Relative Location of 25-ton Chemical Explosions at Balapan Using IMS Stations

Lg Body-Wave Magnitude Scaling for the Continental Margin around Korea and Japan

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