Seismogenic strain across the transition from fore-arc slivering to collision in southern Taiwan: SOUTHERN TAIWAN FORE-ARC SLIVERING

Tectonic slivers have profound implications on the mechanical behavior of fore arcs and subduction zones. Southern Taiwan is characterized by precollision fore-arc slivering that likely exerts important controls on the evolution of collision. Inversion of focal mechanism solutions for seismogenic
strain reveals spatially partitioned plate motion south of Taiwan, with dip-slip faulting nearer the Manila trench and strike-slip faulting nearer the Luzon arc. To the north these kinematics are less clearly segregated, and both types of faults appear to occur in the same volume of crust. Further north deformation is dominated by oblique slip on potentially reactivated steep reverse faults in the collision zone. Existing work on the active fault zones in Taiwan suggests that the subduction-to-collision transition is marked by a releasing step between the strike-slip fault that bounds the fore-arc sliver and the oblique thrusts of the collision zone. This configuration may help to explain the lack of fore-arc basement and cover exposed in the suture zone marked by the Longitudinal Valley.