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Los mega-terremotos rompen las megatrusts planas
Quentin Bletery1, Amanda M Thomas2, Alan W Rempel2
1Department of Earth Sciences, University of Oregon, 1272 University of Oregon, Eugene, OR 97403, USA. qbletery@uoregon.edu.
Science (New York, N.Y.)
|November 26, 2016
Resumen
Los mega-terremotos no requieren una convergencia rápida o una litosfera joven. En cambio, la ruptura del mega-terremoto está vinculada a zonas de subducción planas y de baja curvatura, que promueven una fuerza de cizallamiento homogénea para la ruptura generalizada.
Área de la Ciencia:
- La geofísica
- Sismología
- Tectónica
Sus antecedentes:
- Los terremotos de Sumatra-Andamán en 2004 y Tohoku-Oki en 2011 revelaron un entendimiento incompleto de la dinámica de los mega-terremotos.
- Las suposiciones anteriores vinculaban los mega-terremotos a una convergencia rápida y a una litosfera joven y dinámica, que ahora se desafía.
Objetivo del estudio:
- Para investigar los factores geométricos que controlan la ruptura de un mega terremoto.
- Para identificar la relación entre la geometría de la zona de subducción y la ocurrencia de mega-terremotos.
Principales métodos:
- Cálculo de la curvatura de la interfaz a lo largo de las zonas de subducción global.
- Desarrollo de un modelo analítico simplificado para evaluar la heterogeneidad de la resistencia al corte.
Principales resultados:
- Los mega-terremotos ocurren preferentemente en interfaces de subducción planas (de baja curvatura).
- La curvatura de la interfaz se correlaciona con una mayor heterogeneidad en la resistencia al corte.
- Los megatrusts planos exhiben una resistencia de corte más homogénea, lo que facilita la ruptura simultánea en áreas más grandes.
Conclusiones:
- La geometría de la zona de subducción, específicamente la curvatura de la interfaz, es un factor crítico en la ruptura de un mega terremoto.
- Las interfaces de baja curvatura promueven las condiciones necesarias para la liberación simultánea de tensiones de corte de gran área característica de los mega-terremotos.
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