The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region

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Modeling of broadband seismic waveforms recorded by global and Chilean networks for two moderate crustal earthquakes of the northwestern Sierras Pampeanas shows their focal mechanisms, depths and seismotectonic features. The magnitude Mw 5.8 earthquake on 28 May 2002, located in the eastern flank of...

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Autores principales: Alvarado, P., Ramos, V.A.
Formato: Artículo publishedVersion
Publicado: 2010
Materias:
Andes
Compressive deformation
Decollement levels
Earthquakes
basement rock
compression
crustal structure
decollement
deformation
earthquake epicenter
earthquake magnitude
earthquake mechanism
focal mechanism
modeling
seismic moment
seismicity
seismotectonics
strain
strike-slip fault
waveform analysis
Ambato
Argentina
Catamarca
Sierras Pampeanas
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00044822_v67_n4_p461_Alvarado
https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00044822_v67_n4_p461_Alvarado_oai
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Repositorio Digital de la Universidad de Buenos Aires (UBA) de Universidad de Buenos Aires
id I28-R145-paper_00044822_v67_n4_p461_Alvarado_oai
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spelling I28-R145-paper_00044822_v67_n4_p461_Alvarado_oai2024-08-16 Alvarado, P. Ramos, V.A. 2010 Modeling of broadband seismic waveforms recorded by global and Chilean networks for two moderate crustal earthquakes of the northwestern Sierras Pampeanas shows their focal mechanisms, depths and seismotectonic features. The magnitude Mw 5.8 earthquake on 28 May 2002, located in the eastern flank of the sierra de Velasco and the Mw 6.2 earthquake on 7 September 2004, with epicenter in the southwestern part of the sierra de Ambato, have shallow focal depths of 10 and 8 km, respectively. These results combined with the historical seismicity of the region allow us to estimate the deep structure of the Sierras Pampeanas in the study region. The seismic analyses together with interpretations of the surface structure and previous neotectonic studies ruled out extensional or strike slip deformation as the main responsible mechanism of the Present structure of this sector of the sierras de Ambato and Velasco in the northwestern Sierras Pampeanas. The comparison between the Nazca-South America plate convergence orientation as well as GPS velocities in the upper plate with the summation of the seismic moment tensor for the largest seismic energy released by crustal earthquakes of this region in the last 30 years, shows a clockwise rotation of 50° of the average P-axis orientation from the convergence orientation to the northeast suggesting important strain partition. This partition is controlled by the Eopaleozoic basement fabric, which has guided the orientation and vergence of the Andean faults. Fil:Ramos, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. application/pdf http://hdl.handle.net/20.500.12110/paper_00044822_v67_n4_p461_Alvarado info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar Rev. Asoc. Geol. Argent. 2010;67(4):461-472 Andes Compressive deformation Decollement levels Earthquakes basement rock compression crustal structure decollement deformation earthquake epicenter earthquake magnitude earthquake mechanism focal mechanism modeling seismic moment seismicity seismotectonics strain strike-slip fault waveform analysis Ambato Argentina Catamarca Sierras Pampeanas The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00044822_v67_n4_p461_Alvarado_oai
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-145
collection Repositorio Digital de la Universidad de Buenos Aires (UBA)
topic Andes
Compressive deformation
Decollement levels
Earthquakes
basement rock
compression
crustal structure
decollement
deformation
earthquake epicenter
earthquake magnitude
earthquake mechanism
focal mechanism
modeling
seismic moment
seismicity
seismotectonics
strain
strike-slip fault
waveform analysis
Ambato
Argentina
Catamarca
Sierras Pampeanas
spellingShingle Andes
Compressive deformation
Decollement levels
Earthquakes
basement rock
compression
crustal structure
decollement
deformation
earthquake epicenter
earthquake magnitude
earthquake mechanism
focal mechanism
modeling
seismic moment
seismicity
seismotectonics
strain
strike-slip fault
waveform analysis
Ambato
Argentina
Catamarca
Sierras Pampeanas
Alvarado, P.
Ramos, V.A.
The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region
topic_facet Andes
Compressive deformation
Decollement levels
Earthquakes
basement rock
compression
crustal structure
decollement
deformation
earthquake epicenter
earthquake magnitude
earthquake mechanism
focal mechanism
modeling
seismic moment
seismicity
seismotectonics
strain
strike-slip fault
waveform analysis
Ambato
Argentina
Catamarca
Sierras Pampeanas
description Modeling of broadband seismic waveforms recorded by global and Chilean networks for two moderate crustal earthquakes of the northwestern Sierras Pampeanas shows their focal mechanisms, depths and seismotectonic features. The magnitude Mw 5.8 earthquake on 28 May 2002, located in the eastern flank of the sierra de Velasco and the Mw 6.2 earthquake on 7 September 2004, with epicenter in the southwestern part of the sierra de Ambato, have shallow focal depths of 10 and 8 km, respectively. These results combined with the historical seismicity of the region allow us to estimate the deep structure of the Sierras Pampeanas in the study region. The seismic analyses together with interpretations of the surface structure and previous neotectonic studies ruled out extensional or strike slip deformation as the main responsible mechanism of the Present structure of this sector of the sierras de Ambato and Velasco in the northwestern Sierras Pampeanas. The comparison between the Nazca-South America plate convergence orientation as well as GPS velocities in the upper plate with the summation of the seismic moment tensor for the largest seismic energy released by crustal earthquakes of this region in the last 30 years, shows a clockwise rotation of 50° of the average P-axis orientation from the convergence orientation to the northeast suggesting important strain partition. This partition is controlled by the Eopaleozoic basement fabric, which has guided the orientation and vergence of the Andean faults.
format Artículo
Artículo
publishedVersion
author Alvarado, P.
Ramos, V.A.
author_facet Alvarado, P.
Ramos, V.A.
author_sort Alvarado, P.
title The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region
title_short The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region
title_full The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region
title_fullStr The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region
title_full_unstemmed The Andean structure of the Sierras Pampeanas based on earthquake focal mechanisms in their Northwestern region
title_sort andean structure of the sierras pampeanas based on earthquake focal mechanisms in their northwestern region
publishDate 2010
url http://hdl.handle.net/20.500.12110/paper_00044822_v67_n4_p461_Alvarado
https://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00044822_v67_n4_p461_Alvarado_oai
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AT alvaradop andeanstructureofthesierraspampeanasbasedonearthquakefocalmechanismsintheirnorthwesternregion
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