Mud volcanoes along the Chishan fault in Southwestern Taiwan: A release bend model

Abstract Both land and offshore mud volcanoes have been investigated thoroughly in southwestern Taiwan in terms of morphological expression, spatial distribution, composition, and evasion flux of extruded material. The interactive relationship between mud volcanoes and their associated structures, however, has rarely been examined. This study proposes a release bend model that explains the spatial distribution and relative activity of mud volcanoes along the Chishan Fault, southwestern Taiwan. The surface movement of the Chishan Fault and mud volcano activity were monitored by GPS stations and gas flux measurements, respectively. The resistivity sub-structure of strata across the fault was investigated by the magnetotelluric (MT) method and resistivity image profiling (RIP). Analytical results support the contention that extensional activity at the release bend provides openings to fissures associated with the Chishan Fault, thereby increasing the potential for a mud volcano. The proposed model may facilitate future exploration of mud volcanoes.