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La búsqueda telesísmica de los precursores lentos de los grandes terremotos
Science (New York, N.Y.)
|December 2, 1994
Resumen
Los grandes terremotos pueden tener precursores de deformación lentos y suaves. El análisis de 107 terremotos reveló 20 eventos con precursores lentos, en su mayoría vinculados a los sistemas de cordilleras oceánicas, lo que sugiere eventos de ruptura compuesta.
Área de la Ciencia:
- Sismología Sismología Sismología.
- La geofísica es la geofísica.
- La tectónica es la tectónica.
Sus antecedentes:
- Los grandes terremotos a veces exhiben anomalías sísmicas de baja frecuencia que preceden a su ruptura principal.
- Estas anomalías sugieren eventos de deformación lentos y suaves que ocurren antes del origen sísmico de alta frecuencia.
- Comprender estos precursores es crucial para la física de los terremotos y la evaluación de los peligros.
Objetivo del estudio:
- Investigar la ocurrencia y las características de los precursores sísmicos lentos en los terremotos de foco superficial.
- Para determinar la asociación de estos precursores lentos con entornos tectónicos específicos.
- Para caracterizar la naturaleza de los terremotos que exhiben una lenta deformación precursora.
Principales métodos:
- Análisis de espectros sísmicos de baja frecuencia de 107 terremotos de foco superficial.
- Evaluación estadística (nivel de confianza del 95 por ciento) para identificar precursores lentos significativos.
- Correlación de los eventos lentos identificados con sus entornos tectónicos (transformación de la cresta oceánica y sistemas de grietas continentales).
Principales resultados:
- Veinte de los 107 terremotos analizados mostraron precursores lentos estadísticamente significativos.
- Diecinueve de estos eventos precursores lentos se asociaron con el sistema de transformación de la cresta oceánica.
- Se identificó un evento precursor lento en una falla de transformación intracontinental dentro del sistema de Rift de África Oriental.
Conclusiones:
- Los precursores sísmicos lentos son identificables en un subconjunto de los grandes terremotos.
- Estos terremotos lentos están predominantemente relacionados con el sistema activo de transformación de la cresta oceánica y las grietas continentales.
- Los terremotos con precursores lentos parecen ser eventos compuestos, iniciados por una lenta deformación litosférica que precede a una rápida ruptura.
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