Seismicity and Arrival-Time Residuals From the Victoria Earthquake of June 9, 1980

Abstract

We have studied hypocenter distribution in space and time of the aftershock activity from the Victoria Earthquake of June 9, 1980. We conclude that the main event excited aftershocks in several pre-existing nests at the northwest end of the Cerro Prieto Fault, but no significant activity occurred a.t the immediate neighborhood of the main event. The depth of the aftershocks increases with the distance from the northwest end of the fault and this feature might be related with the higher temperatures and the spreading center located between the ends of the Imperial and Cerro Prieto Faults.
The significance of the arrival-times . residuals for local and regional stations is
discussed both for P and S-waves and the importance of obtaining station corrections is mphasized. The non-uniqueness in determining a structure which minimizes the residuals is illustrated. We present two different structures Which satisfy the local data.


Hemos estudiado la distribucion en espacio y tiempo de hipocentros de replicas del sismo Victoria del 9 de j-unio de 1980. Conclulmos que el evento principal excito las replicas en varios nidos pre-existentes sobre el extremo noroeste de la falla de Cerro Prieto, pero no hubo actividad significativa en la vecindad inmediata del evento principal. La profundidad de las replicas aumenta con la distancia desde el extremo noroeste de la falla, caracteristica que podrla relacionarse con las temperaturas mas altas y el centro de dispersion localizado entre los extremos de las fallas Imperial y Cerro Prieto.
Se discute el significado de los residuos de tiempos de llegada, tanto para las ondas P como S, en estaciones locales y regionales, y se enfatiza la importancia de hacer correciones de estaclon. Se ilustra la no unicidad en la determinacion de la estructura que minimice los residuos. Se presentan dos estructuras diferentes que satisfacen los datos locales.