Neotectonic implications and regional stress field constraints on mud volcanoes in offshore southwestern Taiwan

Recently discovered numerous mud volcanoes (MVs) and mud diapirs (MDs) in SW Taiwan, both onshore and offshore, show eruption lineaments suspected to be related to neotectonic processes. Spatial and temporal distribution of the MVs eruption events shows an obvious switch of the lineament orientation from NNE-, NE-, N-S-, NW- and E-W-trending in N-S direction. The mud volcanoes have experienced multi-stage eruptions, and should have occurred <50 km from the earthquake rupture zones. Along with the weakness zones, the intrusion appears to have occurred on the possible vertical feeder dikes along N25°E and N30°W directions. In this paper, the Coulomb stress changes have been employed to calculate these earthquakes to model the relationship between the fractures and volcanoes, and the source fault geometry of a total of 15 earthquakes constructed from the Globe CMT center and USGS Earthquake and Hazard Program. According to the regional fault geometry, we built the receiver feeder dikes parameters as 330/25/0 and 25/25/0 in strike/dip/rake directions, respectively. Coulomb normal stress changes were computed for the short-time eruption analysis and strain stress changes for the long-scale eruption assessment. Our results indicate that the stress changes are sensitive to the distribution of the eruption events and the Coulomb stress change should be able to facilitate prediction of the future eruptions triggered by the seismicity activities. Finally, the schematic model we proposed well demonstrated the neotectonic effects and regional stress field constraints on the MVs eruption mechanism.