Reconstruction of fault slip of the September 21st, 1999, Taiwan earthquake in the asphalted surface of a car park, and co-seismic slip partitioning

The deformation in the asphalted surface of a car park near Wufeng (24°1′N, 120°41′E) reveals the three-dimensional behaviour of the surface rupture of the September 21st, 1999, Taiwan earthquake. The N–S striking fault dips 30°E and is reverse, almost dip-slip. It accounts for about one half of the total NW–SE shortening of the whole fault zone. The remaining deformation occurred inside the upthrust block, in a damaged zone less than 3 km wide, and is dominated by N–S left-lateral shear. This distribution of co-seismic deformation highlights fault slip partitioning along an oblique fault zone, at a depth shallower than 1.7 km.