An analysis of 2004 Sumatra earthquake fault plane mechanisms and Indian Ocean tsunami

TLDR

The 2004 Sumatra earthquake and its tsunamis were among the most devastating natural disasters of the last century, and multiple fault‑plane models have been proposed to explain the rupture mechanism. The study aims to use satellite sea‑surface measurements to calibrate and validate fault‑plane and tsunami propagation models. Numerical simulations of tsunami generation and propagation were performed using the proposed fault‑plane models, and an inverse method optimized seafloor displacement based on Jason‑1 and TOPEX/Poseidon data. The optimized fault‑plane model produced tsunami simulations that closely matched satellite observations and tidal‑gage measurements, showing that although the rupture zone was up to 1300 km long, the slip duration and rupture speed were relatively short compared with tsunami propagation timescales.

Abstract

The 2004 Sumatra earthquake and the associated tsunamis are one of the most devastating natural disasters in the last century. Several fault plane models have been suggested to represent the rupture mechanism of the earthquake. During this tsunami event, two satellites flew over Bay of Bengal and provided measurements for sea surface elevation with accuracy better than 4.2 cm. The satellite data provide an opportunity to further calibrate and validate the fault mechanism and tsunami propagation models as well. Thus, based on the proposed fault plane models, a series of numerical simulations for tsunami generation and propagation in the Bay of Bengal have been carried out. In comparison with the satellite data, the numerical results show that although the length of the entire ruptured zone is up to 1300 km long for this earthquake, the duration of slip and the rupture speed are still relatively short in comparison with the time scale and the propagation speed of tsunami and the impulsive fault plane model simulates reasonably well the tsunamis in the deep ocean.An inverse method is developed to optimize the seafloor displacement on the fault plane based on the measurements of satellite Jason-1. Finally, employing the optimized fault plane model, we demonstrate that the tsunami simulation model can produce results that match very well with the measurements of sea surface level by satellite TOPEX/Poseidon and available tidal gage measurements at Maldives.