Abstract
AbstractSatellite altimetry measurements of sea surface heights for the first-time captured the Indian Ocean tsunami generated from the December 2004 great Sumatra earthquake. Analysis of the sea surface height profile suggests that the tsunami source, or the seafloor deformation, of the great earthquake propagated to the north at an extremely slow speed of less than 1 km/sec on average for the entire 1300-km-long segment along the northern Sumatra-Nicobar-Andaman Trench. The extremely slow propagation speed produces a very long duration of tens minutes, longer than earthquake source duration estimated (480–500 sec) from short-periodP-wave radiation. The satellite altimetry data requires a total seismic moment of 9.86 × 1022Nm (Mw=9.3). This estimate is approximately 2.5 times larger than the value from long-period surface wave analysis but nearly the same as that from the ultra-long-period normal mode study. The maximum amount of slip (∼30 m) is identified in an offshore region closest to the northern most part of Sumatra where the largest tsunami run-up heights were observed.
Highlights
A great earthquake occurred northwest of Sumatra at0:59 UTC, December 26, 2004
The best-fit solutions suggest that the tsunami source did not reach near northernmost subfault E14
The northern extent and propagation velocity of the tsunami source can be examined by tsunami travel times at northern tide gauge stations
Summary
A great earthquake occurred northwest of Sumatra at0:59 UTC, December 26, 2004. USGS/NEIC (UnitedStates Geological Survey/National Earthquake Information Center) and Harvard University assigned a momentmagnitude (Mw) of 9.0 to this earthquake. The tsunami travel times at tide gauge stations around the Indian Ocean, suggested that the tsunami source area was confined with the southern 600 to 800 km zone (Lay et al, 2005). We analyze the SSH data from the two satellites to investigate heterogeneous source model of the Indian Ocean tsunami.
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