An Interpretation of the 1999 Chi-Chi Earthquake in Taiwan Based on the Thin-Skinned Thrust Model


The 1999 Chi-Chi earthquake (ML = 7.3) which occurred in central Taiwan marks the island¡¦s largest inland seismic event of the twentieth century. The Chi-Chi earthquake had three notable characteristics: 1) its source depth was very shallow (8 km), with aftershocks distributed in a semi-circular belt surrounding the Peikang basement high; 2) it triggered a 90 km long, north-south trending, active fault (the Chelungpu fault), mostly of the thrust type. Its hanging wall side suffered much larger distortions than the foot wall side; and 3) the fault trace bent toward the northeast at its northern tip 50 km away from the source, where the largest surface rupture occurred (9.8m).

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