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Detección sísmica de zonas rígidas en la parte superior del núcleo central
1Department of Earth Sciences, University of California, Santa Cruz, CA 95064, USA. srost@es.ucsc.edu
Science (New York, N.Y.)
|December 1, 2001
Resumen
Los datos sísmicos revelan zonas rígidas en la parte superior del núcleo externo de la Tierra. Estas finas capas sólidas ricas en hierro pueden influir en la nutación de la Tierra y la convección del núcleo externo.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología Sismología.
- Ciencias de la Tierra Ciencias de la Tierra Ciencias de la Tierra
Sus antecedentes:
- El núcleo externo de la Tierra está compuesto principalmente de hierro líquido y níquel.
- Comprender el límite núcleo-manto es crucial para interpretar la propagación de las ondas sísmicas.
- Estudios anteriores han sugerido heterogeneidad en el límite núcleo-manto.
Objetivo del estudio:
- Para investigar las propiedades físicas del núcleo exterior superior.
- Para identificar estructuras rígidas potenciales en el límite núcleo-manto.
- Para explorar las implicaciones de estas estructuras en la dinámica de la Tierra.
Principales métodos:
- Análisis de las formas de onda sísmica de los terremotos de Tonga y Fiji registrados en el norte de Australia.
- Modelado de formas de onda ScP para inferir propiedades del núcleo externo.
- Utilizando datos de matrices sísmicas para detectar la propagación de ondas S en el núcleo más externo.
Principales resultados:
- Hay evidencia de zonas rígidas delgadas (0,12-0,18 km) en la parte superior del núcleo externo.
- Estas zonas exhiben una pequeña velocidad positiva de onda S (0,6-0,8 km/s), lo que permite la propagación de la onda S.
- Las zonas están modeladas como hierro fundido mezclado con material sólido.
Conclusiones:
- Las zonas rígidas identificadas pueden representar alturas topográficas del límite núcleo-manto.
- Estas características podrían estar llenas de sedimentos de núcleo ligero.
- Las zonas podrían desempeñar un papel importante en las variaciones de la nutación de la Tierra y la convección del núcleo externo.
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