Dynamic triggering of earthquakes and the role of overpressure fluids in active geothermal areas in Yunnan, China

The Yunnan area is rich in geothermal fluids, and thus seismicity in this region is considered to be sensitive to stress turbulence by earth tides and distant strong earthquakes. We have identified 13 distant strong earthquakes out of 110 that have dynamically triggered seismicity with a statistical significance of β value >2 and βe. The triggered seismic clusters show the following features. 1) Most clusters are distributed at special fault locations such as fault ends, fault bends, fault steps, and fault intersections. 2) Some clusters display clear fluid diffusion processes, with an increasing water temperature in nearby wells. 3) The ETAS models show a high proportion of forced seismicity and a weak dependence on magnitude for aftershock productivity. These results suggest that the triggered seismicity in the Yunnan area tends to concentrate in specific fault structures with enhanced fluid permeability, where the presence of overpressured fluids possibly makes the seismicity sensitive to dynamic stress triggering.