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Flujo paralelo de zanja y anisotropía sísmica en los sistemas de subducción de las Marianas y los Andes
Erik A Kneller1, Peter E van Keken
1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. ekneller@umich.edu
Nature
|December 22, 2007
Resumen
El flujo tridimensional del manto, impulsado por una compleja geometría de losas en zonas de subducción como las Marianas y los Andes del Sur, explica los patrones de anisotropía sísmica observados. Esta investigación vincula el movimiento de las placas tectónicas con la dinámica del manto.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología Sismología.
- La tectónica es la tectónica.
Sus antecedentes:
- La división de las ondas de corte revela anisotropía sísmica en las zonas de subducción.
- Los patrones de anisotropía cerca de las zonas de subducción de las Marianas y los Andes del Sur muestran direcciones rápidas paralelas a la zanja cerca de la zanja y anisotropía perpendicular a la zanja en el arco posterior.
- Las variaciones longitudinales en la geometría de la losa son significativas en estos sistemas.
Objetivo del estudio:
- Para investigar el vínculo entre la geometría de la losa y los procesos de arrastre en estado sólido en el manto.
- Para explicar los patrones de anisotropía sísmica observados utilizando modelos tridimensionales de zonas de subducción.
Principales métodos:
- Análisis de las mediciones de división de onda de corte.
- Desarrollo y aplicación de modelos totalmente tridimensionales de zonas de subducción no newtonianas.
Principales resultados:
- Modelado fuerte trinchera-paralelo que se extiende en la cuña del manto debido a la curvatura de la losa y la inmersión poco profunda.
- Se observaron rotaciones abruptas en direcciones de estiramiento, consistentes con los datos de anisotropía sísmica.
- Demostró que el flujo tridimensional inducido por variaciones en la geometría de la losa puede explicar la anisotropía observada.
Conclusiones:
- Las variaciones longitudinales en la geometría de la losa son un conductor principal del flujo tridimensional del manto debajo de las zonas de subducción.
- Este patrón de flujo explica con éxito la anisotropía sísmica observada, incluidas las mediciones de división de onda de cizallamiento.
- Los sistemas de subducción de las Marianas y los Andes del Sur sirven como ejemplos clave para comprender esta relación.
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