The effect of subduction coupling zone on the Sunda fore-arc and its surrounding area is modeled using finite element analysis. Based on the simulation results, which are compared with GPS survey, seismological data and geological analysis, the authors quantitatively analyze the distribution of strain intensity and direction of principal strain of the oft-com:office:smarttags" />Sumatra and its surrounding area. Then, the relationship between the area of subduction coupling zone and tectonic evolution is discussed accordingly. The model consists of lithosphere and upper mantle of athenosphere with visco-plasticity properties. The lithosphere includes the continental lithospheric, the oceanic lithospheric and subducted slabs. The results are as follows: 1) by adjusting the area of subduction coupling zone, the authors find out that with coupling area increasing, the value of strain intensity tends to increase. Meanwhile, the distribution of strain field in the other areas can be affected by increase of strain intensity. Therefore, the Sumatra fore-arc shows an obvious segmentation of strain intensity, which corresponds to the rupture pattern of the Sumatra earthquake belt; 2) there is a difference in principal direction of strain between the north and the south of Sumatra, which results from the integrated effects of various subduction velocity, direction, configuration and coupling area in different regions along the subduction zone; and 3) although the northern Sumatra is in a weak coupling condition based on the authors’ simulation results, there still exists a vertical negative displacement influenced by the subduction. The result shows that the area is a tectonic environment of the development of tsunami after earthquake.
