Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory
Autor(a) principal: | |
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Data de Publicação: | 2004 |
Outros Autores: | , |
Tipo de documento: | Artigo de conferência |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10174/6555 |
Resumo: | The directivity effects, a characteristic of finiteness seismic sources, are generated by the rupture in preferential directions. Those effects are manifested through different cadencies in the seismological measures from azimuthally distributed stations. The apparent durations are expressed as (e.g. Aki and Richards, 1980), (1), where L, v, c and ??are, respectively, the fault length, the rupture velocity, the wave velocity and the angle between rupture direction and ray. This time duration can be measured directly from waveform or indirectly from Relative Source Time Function (RSTF). Equation (1) is deduced from a simple source model (Haskell model) that considers unidirectional uniform rupture propagation and a homogeneous elastic isotropic media. If we consider a more general propagation model, with spherical concentric layers, we obtain (2), where p is the ray parameter and the earth radius. Similar equation can be obtained through physical considerations about a model composed by a sequence of subevents unilater- ally distributed along a line (Doppler Effect). Based on the same considerations we can do a more detailed analysis through (3), where is the time interval between 2 identified pulses in the rupture referential and j indicate the number of station. Based on this theory, we have developed a computational code DIRDOP (DIRectivity DOPpler effect) which determines the rupture direction and velocity from pulse durations observed in waveforms or RSTF. We used this code to analyse recent major seismic events including the unilateral 23 June, 1999 Arequipa (Peru, Mw=8.2) earthquake and the bilateral 21 May 2003 Boumerdes (Algeria, Mw=6.7) earthquake amongst others. The results are similar to those obtained by other methods. |
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Seismic Source Directivity from Doppler Effect Analysis, Part I: TheoryRupture VelocityDirectivityDoppler EffectThe directivity effects, a characteristic of finiteness seismic sources, are generated by the rupture in preferential directions. Those effects are manifested through different cadencies in the seismological measures from azimuthally distributed stations. The apparent durations are expressed as (e.g. Aki and Richards, 1980), (1), where L, v, c and ??are, respectively, the fault length, the rupture velocity, the wave velocity and the angle between rupture direction and ray. This time duration can be measured directly from waveform or indirectly from Relative Source Time Function (RSTF). Equation (1) is deduced from a simple source model (Haskell model) that considers unidirectional uniform rupture propagation and a homogeneous elastic isotropic media. If we consider a more general propagation model, with spherical concentric layers, we obtain (2), where p is the ray parameter and the earth radius. Similar equation can be obtained through physical considerations about a model composed by a sequence of subevents unilater- ally distributed along a line (Doppler Effect). Based on the same considerations we can do a more detailed analysis through (3), where is the time interval between 2 identified pulses in the rupture referential and j indicate the number of station. Based on this theory, we have developed a computational code DIRDOP (DIRectivity DOPpler effect) which determines the rupture direction and velocity from pulse durations observed in waveforms or RSTF. We used this code to analyse recent major seismic events including the unilateral 23 June, 1999 Arequipa (Peru, Mw=8.2) earthquake and the bilateral 21 May 2003 Boumerdes (Algeria, Mw=6.7) earthquake amongst others. The results are similar to those obtained by other methods.2012-12-06T17:31:01Z2012-12-062004-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/conferenceObjecthttp://hdl.handle.net/10174/6555http://hdl.handle.net/10174/6555engCaldeira B., M. Bezzeghoud and J. Borges, 2004. Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory. XXIX General Assembly of the European Seismological Commission (ESC), 13-17 September, Potsdam, Germany.naonaonaobafcc@uevora.ptmourad@uevora.ptjborges@uevora.pt249Caldeira, BBezzeghoud, MBorges, JFinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-01-03T18:45:58Zoai:dspace.uevora.pt:10174/6555Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:01:14.025015Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
title |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
spellingShingle |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory Caldeira, B Rupture Velocity Directivity Doppler Effect |
title_short |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
title_full |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
title_fullStr |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
title_full_unstemmed |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
title_sort |
Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory |
author |
Caldeira, B |
author_facet |
Caldeira, B Bezzeghoud, M Borges, JF |
author_role |
author |
author2 |
Bezzeghoud, M Borges, JF |
author2_role |
author author |
dc.contributor.author.fl_str_mv |
Caldeira, B Bezzeghoud, M Borges, JF |
dc.subject.por.fl_str_mv |
Rupture Velocity Directivity Doppler Effect |
topic |
Rupture Velocity Directivity Doppler Effect |
description |
The directivity effects, a characteristic of finiteness seismic sources, are generated by the rupture in preferential directions. Those effects are manifested through different cadencies in the seismological measures from azimuthally distributed stations. The apparent durations are expressed as (e.g. Aki and Richards, 1980), (1), where L, v, c and ??are, respectively, the fault length, the rupture velocity, the wave velocity and the angle between rupture direction and ray. This time duration can be measured directly from waveform or indirectly from Relative Source Time Function (RSTF). Equation (1) is deduced from a simple source model (Haskell model) that considers unidirectional uniform rupture propagation and a homogeneous elastic isotropic media. If we consider a more general propagation model, with spherical concentric layers, we obtain (2), where p is the ray parameter and the earth radius. Similar equation can be obtained through physical considerations about a model composed by a sequence of subevents unilater- ally distributed along a line (Doppler Effect). Based on the same considerations we can do a more detailed analysis through (3), where is the time interval between 2 identified pulses in the rupture referential and j indicate the number of station. Based on this theory, we have developed a computational code DIRDOP (DIRectivity DOPpler effect) which determines the rupture direction and velocity from pulse durations observed in waveforms or RSTF. We used this code to analyse recent major seismic events including the unilateral 23 June, 1999 Arequipa (Peru, Mw=8.2) earthquake and the bilateral 21 May 2003 Boumerdes (Algeria, Mw=6.7) earthquake amongst others. The results are similar to those obtained by other methods. |
publishDate |
2004 |
dc.date.none.fl_str_mv |
2004-01-01T00:00:00Z 2012-12-06T17:31:01Z 2012-12-06 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/conferenceObject |
format |
conferenceObject |
status_str |
publishedVersion |
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http://hdl.handle.net/10174/6555 http://hdl.handle.net/10174/6555 |
url |
http://hdl.handle.net/10174/6555 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
Caldeira B., M. Bezzeghoud and J. Borges, 2004. Seismic Source Directivity from Doppler Effect Analysis, Part I: Theory. XXIX General Assembly of the European Seismological Commission (ESC), 13-17 September, Potsdam, Germany. nao nao nao bafcc@uevora.pt mourad@uevora.pt jborges@uevora.pt 249 |
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info:eu-repo/semantics/openAccess |
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openAccess |
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reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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1799136495680880640 |