The structure beneath the collision suture in central eastern Taiwan
Speaker: Kuei-Mei Lin
Abstract
The Longitudinal Valley of central eastern Taiwan is sandwiched between the Central Range of the Eurasian plate and the Costal Range of the Philippine Sea plate. It is considered as the collision suture between the two fast converging plates. The active collision between the two plates in eastern Taiwan has been explored from the recently determined 3D velocity images and relocated hypocenters. And the anomalous Pn waves in eastern Taiwan suggests that the crust beneath the collision zone suture must be very thin and the upper mantle beneath the Longitudinal Valley must be relatively elevated compared with that beneath the other parts of Taiwan.
The northern collision zone marks the transition region from plate collision to plate subduction further to the north. The southern collision zone marks the transition region from eastward subduction into plate collision. And the central collision zone is creeping and aseismic, which can be attributed to the high heat flow and geothermal activity during an interseismic period since the 1951 Taitung earthquake.Reference
K. H. Kim, J. M. Chiu, J. Pujol, and K. C. Chen (2006) Polarity reversal of active plate boundary and elevated oceanic upper mantle beneath the collision suture in central eastern Taiwan. Bull. Seism. Soc. Am. 96 , No. 3, 796-806
W. T. Liang, J. M. Chiu, and Kwanghee Kim (2007) Anomalous Pn wave observed in eastern Taiwan: Implications of a thin crust and elevated oceanic upper mantle beneath the active collision-zone suture. Bull. Seism. Soc. Am. 97 , No. 4, 1370-1377