The dual source region for the 2004 Sumatra tsunami

Abstract

Wave arrival times obtained from coastal tide gage and satellite altimetry records for the Indian Ocean are used to delineate the source region for the December 26, 2004 Sumatra tsunami. Findings define a curved, 250‐km wide, 1000‐km long tsunami source region centered over the Sunda Subduction Zone, which closely matches the seismic source estimated from broadband geophysical data. Imbedded in this general region are “hot spots” associated with the southern fast‐slip and northern slow‐slip domains which served as distinct source areas for the destructive waves that inundated the coast of the Indian Ocean.

Brief communication "Seismic and acoustic-gravity signals from the source of the 2004 Indian Ocean Tsunami"

“…For example, for the great Sumatra-Andaman earthquake of 26 December 2004, a vertical displacement of the seafloor of up to 10 m was estimated (Bilham et al, 2005;Fine et al, 2005;Song et al, 2005or Heki et al, 2006. The rupture area extended over about 1500 × 200 km 2 .…”

Analysis of tide gauge records from the December 2004 Indian Ocean tsunami

“…The UHSLC data used has the predicted tidal component removed but the NTC did not. These six stations all have clean deep ocean paths between them and the tsunamigenic source zone [Fine et al, 2005]. The tsunami wave they sampled was similar to that which the Jason and TOPEX/Poseidon satellites sampled and two had seismic stations nearby which clearly recorded the tsunami.…”

Method of calculating tsunami travel times in the Andaman Sea region

“…Measurements from tide gauge stations on the coast of Thailand were not used because of inadequate resolution (Fine et al 2005); it is difficult to accurately determine times from these low-speed analog paper records (Rabinovich and Thomson 2007), as the times recorded on some of the sheets are imprecise (Tsuji et al 2006). Deviations between the calculated and observed travel times proved to be satisfactorily small formost of the targets, including those in the open sea and in coastal areas (Table 3).…”

“…Of the sources of travel times observed in the Andaman Sea region for the 26 December 2004 tsunami, the echosounder record made from the Belgian yacht, Mercator (Rabinovich and Thomson 2007), and the tsunami photographs taken in Khao Lak and Koh Lanta (Heinrich Grosskopf 2007, private communication) are considered the most reliable (Fine et al 2005). Therefore, data from these sources were used to calibrate the model by fine tuning the velocity correction factor (F v = 1.6).…”