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Slow postseismic recovery of geoid depression formed by the 2004 Sumatra‐Andaman Earthquake by mantle water diffusion
Author(s) -
Ogawa Ryoko,
Heki Kosuke
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl029340
Subject(s) - geoid , geology , mantle (geology) , geodesy , gravity anomaly , seismology , geophysics , paleontology , oil field , measured depth
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 H 2 O 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.