Paleoseismology study of the ranong fault zone in Prachuap Khiri Khan Province, South Central Thailand

Abstract

© 2011 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. The Ranong Fault Zone represents active sets of currently sinistral strike-slip faults in the southern Thailand. It consists of several segments with northeast-southwest orientations. A trench in Prachuap Khiri Khan Province in south central Thailand is excavated for paleoseismology study on one segment of the Ranong Fault Zone. The result from this study suggests evidences of the faults' displacements cutting through a series of bedrock with offsets up to 50 cm. The age of thisearthquake event is between before 12,400 ± 1,300 and before 9,600 ± 700 years B.P. The calculations of the maximum credible earthquake magnitudes from the surface rupture lengths and the faults' displacements discovered in the trench on this fault segment suggest values between 6.1 and 6.6Mw.