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Terremotos dentro de la losa: deshidratación de la losa de Cascadia
Leiph A Preston1, Kenneth C Creager, Robert S Crosson
1Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA. preston@ess.washington.edu
Science (New York, N.Y.)
|November 15, 2003
Resumen
Los investigadores han mapeado la estructura sísmica en 3D de la placa Juan de Fuca en Washington. Esto revela dos orígenes distintos de los terremotos: la deshidratación de la serpentinita en el manto y la transformación del basalto en eclogita en la corteza.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología.
- La tectónica es la tectónica.
Sus antecedentes:
- La placa Juan de Fuca se subduce debajo de América del Norte, generando una actividad sísmica compleja.
- Comprender la estructura de la placa de subducción es clave para descifrar los mecanismos de los terremotos.
Objetivo del estudio:
- Determinar la estructura tridimensional de velocidad de onda de compresión y la geometría del reflector de la placa subductora Juan de Fuca.
- Para investigar los orígenes de los terremotos intraslab en la zona de subducción de Cascadia.
Principales métodos:
- Inversión simultánea de los tiempos de recorrido de las ondas sísmicas refractadas y ampliamente reflejadas.
- Modelado de velocidad sísmica 3D y reubicación de terremotos.
Principales resultados:
- Identificó el límite entre la corteza y el manto (Moho) de la placa subductora Juan de Fuca.
- Separó los terremotos intraslab en dos grupos distintos en función de su ubicación en relación con el Moho.
- Los terremotos de inmersión ascendente de la profundidad de 45 km de Moho ocurren en el manto oceánico subducido; los terremotos de inmersión descendente ocurren en la corteza subducida.
Conclusiones:
- Los terremotos up-dip de Intraslab están relacionados con la deshidratación de la serpentinita.
- Los terremotos de Intraslab hacia abajo se atribuyen a la transformación de basalto a eclogita.
- Proporciona un nuevo marco para comprender la generación de terremotos en la zona de subducción de Cascadia.
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