Slow postseismic recovery of geoid depression formed by the 2004 Sumatra‐Andaman Earthquake by mantle water diffusion
Slow postseismic recovery of geoid depression formed by the 2004 Sumatra‐Andaman Earthquake by mantle water diffusion
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DOI：
10.1029/2007gl029340
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发表时间：
2007-03
影响因子：
5.2
通讯作者：
R. Ogawa;K. Heki
中科院分区：
文献类型：
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作者：
R. Ogawa;K. Heki
地震伴随着质量的重新分布，并导致重力场和大地水准面（与平均海面重合的等位面）形状的变化。 2004 年苏门答腊-安达曼地震后，卫星重力测量检测到了这种同震变化，但人们对地震后大地水准面发生的情况知之甚少。在这里，我们报告了卫星测量中同震大地水准面凹陷的缓慢震后恢复。这不能用简单的后滑或麦克斯韦上地幔的粘性松弛来解释。这表明上地幔中丰富的超临界水的扩散可以松弛同震膨胀和压缩。这种同震大地水准面起伏的自愈系统是水在地幔中的全新作用，将显着减少地震造成的地球自转轴永久偏移的量。
Earthquakes are accompanied with mass redistributions and cause changes in gravity field and shape of geoid, an equipotential surface coincident with the mean sea surface. Such coseismic changes were detected by satellite gravimetry after the 2004 Sumatra‐Andaman Earthquake, but little has been known on what happens on geoid after the earthquake. Here we report slow postseismic recovery of coseismic geoid depression from satellite measurements. This cannot be explained with simple afterslip or viscous relaxation of Maxwellian upper mantle. It suggests the relaxation of coseismic dilatation and compression by the diffusion of supercritical H2O abundant in the upper mantle. Such a self‐healing system of coseismic geoid undulations, a brand‐new role of water in mantle, would significantly reduce the amount of permanent shifts of the Earth's rotation axis by earthquakes.