Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S

Only few (six) focal mechanism, in CMT Catalog, have been so far known for intraplate shallow events in the Andean chain close to Chile–Argentina state border at latitudes ∼35° S. We add two more mechanisms, depths and moment magnitudes by carefully analyzing full waveforms of weak events recorded b...

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Autores principales: Villegas A., R.J., Zahradník, J., Nacif, S., Spagnotto, S., Winocur, D., Leiva, M.F.
Formato: JOUR
Materias:
Andean chain
Cordillera Principal
CSPS code
ISOLA
Moment tensor
Waveform inversion
Weak earthquakes
arrival time
border region
earthquake catalogue
earthquake hypocenter
earthquake magnitude
earthquake mechanism
focal mechanism
intraplate process
moment tensor
strike-slip fault
tectonic setting
Argentina
Chile
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_08959811_v71_n_p359_VillegasA
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_08959811_v71_n_p359_VillegasA
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spelling todo:paper_08959811_v71_n_p359_VillegasA2023-10-03T15:43:24Z Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S Villegas A., R.J. Zahradník, J. Nacif, S. Spagnotto, S. Winocur, D. Leiva, M.F. Andean chain Cordillera Principal CSPS code ISOLA Moment tensor Waveform inversion Weak earthquakes arrival time border region earthquake catalogue earthquake hypocenter earthquake magnitude earthquake mechanism focal mechanism intraplate process moment tensor strike-slip fault tectonic setting Argentina Chile Cordillera Principal Only few (six) focal mechanism, in CMT Catalog, have been so far known for intraplate shallow events in the Andean chain close to Chile–Argentina state border at latitudes ∼35° S. We add two more mechanisms, depths and moment magnitudes by carefully analyzing full waveforms of weak events recorded by broad-band stations of the Chile Argentina Geophysical Experiment (southern profile). The moment magnitudes of both events (Mw = 3.6 and 3.7) are lower than the duration magnitudes (Md = 4.0 and 4.29) reported by NEIC. The source depth, constrained by waveforms for one of the studied events (5.5–8.5 km) seems to be considerably shallower than the hypocenter depth located by means of arrival times (∼20 km). The waveform analysis was complemented by first-motion polarities which resulted in an uncertainty assessment of the focal mechanism. Event 1 (2001-11-03) has a strike-slip mechanism with a small normal component and almost vertical nodal planes in the north-south and east-west directions. The north-south nodal plane could be related to the Calabozos faults system. Event 2 (2002-02-16) has a strike-slip mechanism with a small thrust component. The latter event (its subhorizontal nodal plane) could be associated with the El Diablo-El Fierro fault system. Dextral strike-slip solutions are consistent with recent studies in the area. © 2015 Elsevier Ltd JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_08959811_v71_n_p359_VillegasA
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Andean chain
Cordillera Principal
CSPS code
ISOLA
Moment tensor
Waveform inversion
Weak earthquakes
arrival time
border region
earthquake catalogue
earthquake hypocenter
earthquake magnitude
earthquake mechanism
focal mechanism
intraplate process
moment tensor
strike-slip fault
tectonic setting
Argentina
Chile
Cordillera Principal
spellingShingle Andean chain
Cordillera Principal
CSPS code
ISOLA
Moment tensor
Waveform inversion
Weak earthquakes
arrival time
border region
earthquake catalogue
earthquake hypocenter
earthquake magnitude
earthquake mechanism
focal mechanism
intraplate process
moment tensor
strike-slip fault
tectonic setting
Argentina
Chile
Cordillera Principal
Villegas A., R.J.
Zahradník, J.
Nacif, S.
Spagnotto, S.
Winocur, D.
Leiva, M.F.
Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
topic_facet Andean chain
Cordillera Principal
CSPS code
ISOLA
Moment tensor
Waveform inversion
Weak earthquakes
arrival time
border region
earthquake catalogue
earthquake hypocenter
earthquake magnitude
earthquake mechanism
focal mechanism
intraplate process
moment tensor
strike-slip fault
tectonic setting
Argentina
Chile
Cordillera Principal
description Only few (six) focal mechanism, in CMT Catalog, have been so far known for intraplate shallow events in the Andean chain close to Chile–Argentina state border at latitudes ∼35° S. We add two more mechanisms, depths and moment magnitudes by carefully analyzing full waveforms of weak events recorded by broad-band stations of the Chile Argentina Geophysical Experiment (southern profile). The moment magnitudes of both events (Mw = 3.6 and 3.7) are lower than the duration magnitudes (Md = 4.0 and 4.29) reported by NEIC. The source depth, constrained by waveforms for one of the studied events (5.5–8.5 km) seems to be considerably shallower than the hypocenter depth located by means of arrival times (∼20 km). The waveform analysis was complemented by first-motion polarities which resulted in an uncertainty assessment of the focal mechanism. Event 1 (2001-11-03) has a strike-slip mechanism with a small normal component and almost vertical nodal planes in the north-south and east-west directions. The north-south nodal plane could be related to the Calabozos faults system. Event 2 (2002-02-16) has a strike-slip mechanism with a small thrust component. The latter event (its subhorizontal nodal plane) could be associated with the El Diablo-El Fierro fault system. Dextral strike-slip solutions are consistent with recent studies in the area. © 2015 Elsevier Ltd
format JOUR
author Villegas A., R.J.
Zahradník, J.
Nacif, S.
Spagnotto, S.
Winocur, D.
Leiva, M.F.
author_facet Villegas A., R.J.
Zahradník, J.
Nacif, S.
Spagnotto, S.
Winocur, D.
Leiva, M.F.
author_sort Villegas A., R.J.
title Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
title_short Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
title_full Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
title_fullStr Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
title_full_unstemmed Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
title_sort waveform inversion and focal mechanisms of two weak earthquakes in cordillera principal (argentina) between 35° and 35.5° s
url http://hdl.handle.net/20.500.12110/paper_08959811_v71_n_p359_VillegasA
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