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Anisotropía elástica del núcleo interno de la Tierra
Anatoly B Belonoshko1, Natalia V Skorodumova, Anders Rosengren
1Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. anatoly.belonoshko@fysik.uu.se
Science (New York, N.Y.)
|February 9, 2008
Resumen
El núcleo interno de la Tierra exhibe anisotropía sísmica, con ondas sonoras que viajan más rápido a lo largo del eje de giro. Las simulaciones de dinámica molecular revelan que el hierro cúbico centrado en el cuerpo, no el hierro hexagonal, explica esta anisotropía.
Área de la Ciencia:
- La geofísica es la geofísica.
- Ciencia de los materiales Ciencia de los materiales.
- Sismología Sismología Sismología.
Sus antecedentes:
- El núcleo interno sólido de la Tierra es elásticamente anisotrópico.
- Las ondas sísmicas viajan más rápido a lo largo del eje de giro que en el plano ecuatorial.
- Las explicaciones anteriores que involucran cristales de hierro hexagonales son poco probables debido a la isotropía dependiente de la temperatura.
Objetivo del estudio:
- Para investigar la causa de la anisotropía sísmica en el núcleo interno de la Tierra.
- Para evaluar el papel del hierro cúbico centrado en el cuerpo en la anisotropía del núcleo interno.
Principales métodos:
- Simulaciones de dinámica molecular.
- Simulaciones de la propagación de las ondas sísmicas.
- Análisis de las propiedades elásticas del hierro en las condiciones internas del núcleo.
Principales resultados:
- El hierro cúbico centrado en el cuerpo, a pesar de la alta simetría, es altamente anisotrópico para las ondas sonoras.
- Las simulaciones muestran una anisotropía del 12% en el hierro cúbico centrado en el cuerpo.
- Este valor es suficiente para explicar la anisotropía observada en el núcleo interno.
Conclusiones:
- El hierro cúbico centrado en el cuerpo es la causa probable de la anisotropía sísmica del núcleo interno de la Tierra.
- La alta simetría del hierro cúbico centrado en el cuerpo no excluye una significativa anisotropía elástica.
- Este hallazgo concilia los datos experimentales y de simulación con respecto a las propiedades del núcleo interno.
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