Path-specific, dispersion-based velocity models and moment tensors of moderate events recorded at few distant stations: Examples from Brazil and Greece

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F16%3A10330100" target="_blank" >RIV/00216208:11320/16:10330100 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.jsames.2016.07.004" target="_blank" >http://dx.doi.org/10.1016/j.jsames.2016.07.004</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jsames.2016.07.004" target="_blank" >10.1016/j.jsames.2016.07.004</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Path-specific, dispersion-based velocity models and moment tensors of moderate events recorded at few distant stations: Examples from Brazil and Greece

Popis výsledku v původním jazyce

Centroid moment tensor (CMT) determination in intraplate regions like Brazil can be very difficult, because earthquakes are often recorded just at few and distant stations. This paper introduces a methodology for datasets like that. The methodology is based on waveform inversion in which each source-station path has its own velocity model. The 1-D path-specific velocity models are derived from the Rayleigh- and Love-wave dispersion curves. The waveform inversion is accompanied by posterior check of numerous P-wave first-motion polarities. An important innovation is the use of so-called frequency range test. The test basically consists in calculating CMT's for many different frequency ranges to assess the stability and uncertainty of the solution. The method is validated on two Brazilian earthquakes and a well-known Greek event. An offshore event (mb 5.2) in SE Brazil is inverted with four stations, at epicentral distances 300-400 km. The other Brazilian earthquake (mb 4.8 in Central Brazil) is even more challenging only two broadband stations at 800-1300 km are at disposal for waveform inversion. The paper unambiguously demonstrates that the path-specific velocity models significantly increase the reliability of the CMT's. While standard models (e.g. IASP91) typically allow waveform modeling up to epicentral distances of the order of a few (similar to 10) minimum shear wavelengths (MSW), using the path specific velocity models we successfully inverted waveforms up to > 20 MSW. Single-station waveform inversions are thoroughly tested, but multi-station joint inversions are shown to be preferable. The new methodology of this paper, providing a reasonable estimate of focal mechanisms and their uncertainties in case of highly limited waveform data, may find broad applicability in Brazil and elsewhere. (C) 2016 Published by Elsevier Ltd.

Název v anglickém jazyce

Path-specific, dispersion-based velocity models and moment tensors of moderate events recorded at few distant stations: Examples from Brazil and Greece

Popis výsledku anglicky

Centroid moment tensor (CMT) determination in intraplate regions like Brazil can be very difficult, because earthquakes are often recorded just at few and distant stations. This paper introduces a methodology for datasets like that. The methodology is based on waveform inversion in which each source-station path has its own velocity model. The 1-D path-specific velocity models are derived from the Rayleigh- and Love-wave dispersion curves. The waveform inversion is accompanied by posterior check of numerous P-wave first-motion polarities. An important innovation is the use of so-called frequency range test. The test basically consists in calculating CMT's for many different frequency ranges to assess the stability and uncertainty of the solution. The method is validated on two Brazilian earthquakes and a well-known Greek event. An offshore event (mb 5.2) in SE Brazil is inverted with four stations, at epicentral distances 300-400 km. The other Brazilian earthquake (mb 4.8 in Central Brazil) is even more challenging only two broadband stations at 800-1300 km are at disposal for waveform inversion. The paper unambiguously demonstrates that the path-specific velocity models significantly increase the reliability of the CMT's. While standard models (e.g. IASP91) typically allow waveform modeling up to epicentral distances of the order of a few (similar to 10) minimum shear wavelengths (MSW), using the path specific velocity models we successfully inverted waveforms up to > 20 MSW. Single-station waveform inversions are thoroughly tested, but multi-station joint inversions are shown to be preferable. The new methodology of this paper, providing a reasonable estimate of focal mechanisms and their uncertainties in case of highly limited waveform data, may find broad applicability in Brazil and elsewhere. (C) 2016 Published by Elsevier Ltd.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DC - Seismologie, vulkanologie a struktura Země

OECD FORD obor

—

Projekt

<a href="/cs/project/GA14-04372S" target="_blank" >GA14-04372S: Složitost zdrojů tektonických zemětřesení na různých časoprostorových škálách</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of South American Earth Sciences

ISSN

0895-9811

e-ISSN

—

Svazek periodika

71

Číslo periodika v rámci svazku

-

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

15

Strana od-do

344-358

Kód UT WoS článku

000385322400026

EID výsledku v databázi Scopus

2-s2.0-84979019846