Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise

Detalhes bibliográficos
Autor(a) principal: Torres, Ricardo
Data de Publicação: 2013
Outros Autores: Furtado, Augusto, Silva, Hugo, Borges, JF, Caldeira, Bento, Bezzeghoud, Mourad, Carvalho, João
Tipo de documento: Artigo de conferência
Idioma: por
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10174/9163
Resumo: Along his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them produced in large ruptures of offshore structures located southwest of the Portuguese coastline. Among these is the Lisbon earthquake of 1 November 1755 (M∼8.5-8.7), and other moderates earthquakes that were produced by local sources such as the 1344 (M6.0), 1531 (M7.1) and 1909 (M6.0) earthquakes. Previous simulations [1] have shown high velocity amplification in the region. The model used in the simulations was updated from low to high resolution using all the new available geophysical and geotechnical data on the area (seismic reflection, aeromagnetic, gravimetric, deep wells and geological outcrops) [2]. To confirm this model in the areas where it was derived by potential field methods we use broadband ambient noise measurements collected in about 200 points along seven profiles on the LTV basin, six perpendicular and one parallel to the basin axis. We applied the horizontal to vertical (H/V) spectral ratio method [3] to the seismic noise profiles in order to estimate the distribution of amplification in the basin. The H/V curves obtained reveals the existence of two low frequency peaks centered on 0.2 and 1 Hz [4]. These peaks are strongly related with the thickness of Cenozoic and alluvial sediments. The velocity model obtained by inversion of the H/V curves is in good agreement with borehole data, and results obtained using seismic reflection and gravimetric methods. However, aeromagnetic data overestimates the depth of the base of Cenozoic in the areas where it overlies directly the paleozoic basement, which we attribute either to the existence of Mesozoic units or higher magnetic susceptibilities than expected for the Paleozoic. References: [1] Bezzeghoud, M., Borges, J.F., M., Caldeira (2011). Ground motion simulations of the SW Iberia margin: rupture directivity and earth structure effects. Natural Hazards, pages 1–17. doi:10.1007/s11069-011-9925-2 [2] Torres, R.J.G., (2012). Modelo de velocidade da Bacia do Vale do Tejo: uma abordagem baseada no estudo do ruído sísmico ambiental, Master Thesis, Universidade de Évora, 83pp. [3] Nakamura, Y., 1989. A method for dynamic characteristics estimations of subsurface using microtremors on the ground surface, Quarterly Report, RTRI, Japan, v. 30, p. 25-33. [4] J.A. Furtado, Confirmação do modelo da estrutura 3D do Vale Inverior do Tejo a partir de dados de ruído sísmico ambiente, Master Thesis, Universidade de Évora, 136pp, 2010.
id RCAP_f3770f6949614cdb1ce2ba3bf034f758
oai_identifier_str oai:dspace.uevora.pt:10174/9163
network_acronym_str RCAP
network_name_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository_id_str 7160
spelling Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noiseLower Tagus BasinVelocity modelAlong his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them produced in large ruptures of offshore structures located southwest of the Portuguese coastline. Among these is the Lisbon earthquake of 1 November 1755 (M∼8.5-8.7), and other moderates earthquakes that were produced by local sources such as the 1344 (M6.0), 1531 (M7.1) and 1909 (M6.0) earthquakes. Previous simulations [1] have shown high velocity amplification in the region. The model used in the simulations was updated from low to high resolution using all the new available geophysical and geotechnical data on the area (seismic reflection, aeromagnetic, gravimetric, deep wells and geological outcrops) [2]. To confirm this model in the areas where it was derived by potential field methods we use broadband ambient noise measurements collected in about 200 points along seven profiles on the LTV basin, six perpendicular and one parallel to the basin axis. We applied the horizontal to vertical (H/V) spectral ratio method [3] to the seismic noise profiles in order to estimate the distribution of amplification in the basin. The H/V curves obtained reveals the existence of two low frequency peaks centered on 0.2 and 1 Hz [4]. These peaks are strongly related with the thickness of Cenozoic and alluvial sediments. The velocity model obtained by inversion of the H/V curves is in good agreement with borehole data, and results obtained using seismic reflection and gravimetric methods. However, aeromagnetic data overestimates the depth of the base of Cenozoic in the areas where it overlies directly the paleozoic basement, which we attribute either to the existence of Mesozoic units or higher magnetic susceptibilities than expected for the Paleozoic. References: [1] Bezzeghoud, M., Borges, J.F., M., Caldeira (2011). Ground motion simulations of the SW Iberia margin: rupture directivity and earth structure effects. Natural Hazards, pages 1–17. doi:10.1007/s11069-011-9925-2 [2] Torres, R.J.G., (2012). Modelo de velocidade da Bacia do Vale do Tejo: uma abordagem baseada no estudo do ruído sísmico ambiental, Master Thesis, Universidade de Évora, 83pp. [3] Nakamura, Y., 1989. A method for dynamic characteristics estimations of subsurface using microtremors on the ground surface, Quarterly Report, RTRI, Japan, v. 30, p. 25-33. [4] J.A. Furtado, Confirmação do modelo da estrutura 3D do Vale Inverior do Tejo a partir de dados de ruído sísmico ambiente, Master Thesis, Universidade de Évora, 136pp, 2010.EGU General Assembly 20132014-01-02T16:22:06Z2014-01-022013-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/conferenceObjecthttp://hdl.handle.net/10174/9163http://hdl.handle.net/10174/9163porTorres, J., Furtado, A. Silva, H., Borges, J.F., Caldeira, Bento, Bezzeghoud, Mourad, Carvalho, João, Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise, Geophysical Research Abstracts Vol. 15, EGU2013-11271, 2013, EGU General Assembly 7-12 April, Vienna.naonaosimricardojgtorres@gmail.comjaugustado@gmail.comhgsilva@uevora.ptjborges@uevora.ptbafcc@uevora.ptmourad@uevora.ptJoao Carvalho <joao.carvalho@lneg.pt>Torres, RicardoFurtado, AugustoSilva, HugoBorges, JFCaldeira, BentoBezzeghoud, MouradCarvalho, Joãoinfo: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:RCAAP2024-01-03T18:50:55Zoai:dspace.uevora.pt:10174/9163Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:03:18.658698Repositório 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 Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
title Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
spellingShingle Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
Torres, Ricardo
Lower Tagus Basin
Velocity model
title_short Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
title_full Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
title_fullStr Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
title_full_unstemmed Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
title_sort Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise
author Torres, Ricardo
author_facet Torres, Ricardo
Furtado, Augusto
Silva, Hugo
Borges, JF
Caldeira, Bento
Bezzeghoud, Mourad
Carvalho, João
author_role author
author2 Furtado, Augusto
Silva, Hugo
Borges, JF
Caldeira, Bento
Bezzeghoud, Mourad
Carvalho, João
author2_role author
author
author
author
author
author
dc.contributor.author.fl_str_mv Torres, Ricardo
Furtado, Augusto
Silva, Hugo
Borges, JF
Caldeira, Bento
Bezzeghoud, Mourad
Carvalho, João
dc.subject.por.fl_str_mv Lower Tagus Basin
Velocity model
topic Lower Tagus Basin
Velocity model
description Along his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them produced in large ruptures of offshore structures located southwest of the Portuguese coastline. Among these is the Lisbon earthquake of 1 November 1755 (M∼8.5-8.7), and other moderates earthquakes that were produced by local sources such as the 1344 (M6.0), 1531 (M7.1) and 1909 (M6.0) earthquakes. Previous simulations [1] have shown high velocity amplification in the region. The model used in the simulations was updated from low to high resolution using all the new available geophysical and geotechnical data on the area (seismic reflection, aeromagnetic, gravimetric, deep wells and geological outcrops) [2]. To confirm this model in the areas where it was derived by potential field methods we use broadband ambient noise measurements collected in about 200 points along seven profiles on the LTV basin, six perpendicular and one parallel to the basin axis. We applied the horizontal to vertical (H/V) spectral ratio method [3] to the seismic noise profiles in order to estimate the distribution of amplification in the basin. The H/V curves obtained reveals the existence of two low frequency peaks centered on 0.2 and 1 Hz [4]. These peaks are strongly related with the thickness of Cenozoic and alluvial sediments. The velocity model obtained by inversion of the H/V curves is in good agreement with borehole data, and results obtained using seismic reflection and gravimetric methods. However, aeromagnetic data overestimates the depth of the base of Cenozoic in the areas where it overlies directly the paleozoic basement, which we attribute either to the existence of Mesozoic units or higher magnetic susceptibilities than expected for the Paleozoic. References: [1] Bezzeghoud, M., Borges, J.F., M., Caldeira (2011). Ground motion simulations of the SW Iberia margin: rupture directivity and earth structure effects. Natural Hazards, pages 1–17. doi:10.1007/s11069-011-9925-2 [2] Torres, R.J.G., (2012). Modelo de velocidade da Bacia do Vale do Tejo: uma abordagem baseada no estudo do ruído sísmico ambiental, Master Thesis, Universidade de Évora, 83pp. [3] Nakamura, Y., 1989. A method for dynamic characteristics estimations of subsurface using microtremors on the ground surface, Quarterly Report, RTRI, Japan, v. 30, p. 25-33. [4] J.A. Furtado, Confirmação do modelo da estrutura 3D do Vale Inverior do Tejo a partir de dados de ruído sísmico ambiente, Master Thesis, Universidade de Évora, 136pp, 2010.
publishDate 2013
dc.date.none.fl_str_mv 2013-01-01T00:00:00Z
2014-01-02T16:22:06Z
2014-01-02
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
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10174/9163
http://hdl.handle.net/10174/9163
url http://hdl.handle.net/10174/9163
dc.language.iso.fl_str_mv por
language por
dc.relation.none.fl_str_mv Torres, J., Furtado, A. Silva, H., Borges, J.F., Caldeira, Bento, Bezzeghoud, Mourad, Carvalho, João, Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noise, Geophysical Research Abstracts Vol. 15, EGU2013-11271, 2013, EGU General Assembly 7-12 April, Vienna.
nao
nao
sim
ricardojgtorres@gmail.com
jaugustado@gmail.com
hgsilva@uevora.pt
jborges@uevora.pt
bafcc@uevora.pt
mourad@uevora.pt
Joao Carvalho <joao.carvalho@lneg.pt>
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv EGU General Assembly 2013
publisher.none.fl_str_mv EGU General Assembly 2013
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
repository.mail.fl_str_mv
_version_ 1799136516577951744