Current Issue

TECTONIC FRAMEWORK INDUCED BY SHEAR BANDING: A CASE STUDY OF THE SOUTH TAIWAN ISLAND ARC

Tse-Shan Hsu

President, Institute of Mitigation for Earthquake Shear Banding Disasters

Professor, Feng-Chia University, Taiwan, R.O.C., This email address is being protected from spambots. You need JavaScript enabled to view it.

Yu-Chien Wu

Ph.D. Student, Ph.D. Program for Infrastructure Planning and Engineering, 

Feng-Chia University, Taiwan, R.O.C.

Zong-Lin Wu  

Assistant Professor, National Chin-Yi University of Technology, Taiwan, R.O.C

Tsai-Fu Chuang

Associate Professors, Feng-Chia University, Taiwan, R.O.C.

Abstract

The traditional concept of the tectonic framework for the South Taiwan island arc according to which the shallow-sea plate of the South China Sea subducts below the deep-sea plate of the Philippine Sea does not accurately reflect the facts but it has continued to remain in use. In order to address this problem, the South Taiwan island arc is here examined using the GPS velocity vectors distribution map and the results of a shear-banding table simulation test. The results reveal that: (1) under the influence of deep shear banding, the magnitude of GPS velocity vectors induced by the deep-sea plate are larger than the GPS velocity vectors induced by the shallow-sea plate; (2) the current concept of the tectonic framework of South Taiwan that only includes eastward bending of the shallow South China Sea plate and subduction below the South Taiwan island arc and the deep Philippine Sea Plate is inadequate; (3) the tectonic framework should recognize the importance of lateral compression induced by the deep Philippine Sea Plate on the South Taiwan island arc toward the west and generation of a deep shear band that continues to extend toward the west; and (4) the tectonic framework should also incorporate the lateral compression of the shallow South China Sea plate on the South Taiwan island arc and shallow shear banding that terminates at the intersection with the deep shear band. Based on the above conclusions, the authors suggest that the tectonic framework of the South Taiwan island arc proposed in this paper should be adopted so that the tectonic framework is consistent with shear-band displaced landform features.

Keywords: Taiwan island arc, tectonic framework, shear band, GPS velocity vectors.