Artículos de revistas
Lithospheric stress state in South America as inferred from tidal triggering of earthquakes
Lithospheric stress state in South America as inferred from tidal triggering of earthquakes
Autor
Nikolaev, Alexei; Research and Coordinating Center for Seismology and Engineering RAS, Moscow, Russia.
Nikolaev, Vsevolod; Institute of Physics of the Earth RAS, Moscow, Russia.
Institución
Resumen
We present a model fot lithospheric stress state in South America inferred from tidal triggering of earthquakes. The South America plate is attractive for study because the slap pull component should be small and the other components are reasonably isolated geographically. A catalogue of South America earthquakes which containts 23,399 events with M>3.5 has been used for the study of the Earth tide triggering effect. The normalized difference, t, between the number of shocks occurring during positive and nevative phases of tidal vector components is used to estimate the tidal triggering effect. This value t has a mosaic spatial distribution and changes with time. The tidal triggering effect is also connected with a few harmonic components of the Earth tide that differ from area to area. We present maps of the Lode-Nadai coefficient, that characterizes the lithosphere stress state. These maps show a dominant state of tensin along the Cordilleras and rather chaotic distribution in the inner-continental area. The detailed features have a complex character and are not distincitly tied with tectonic elements. The maps of the orientation of compression and tension axes are also obtained using a tidal triggering effect. Se presenta un modelo del estado de esfuerzo en la litosfera sudamericana, con base en el desgatillamiento de sismos por efecto de las mareas. Se utilizó un catálogo de 23,399 temblores de magnitud M>3.5 y se calculó la diferencia entre el número de temblores que ocurre durante fases opuestas de la marea. Se calcularon los coeficientes de Lode-Nadai, que muestran el estado de esfuerzo tensional a lo largo de la Cordillera, y caótico en el interior del continente.