The 2011 Yingjiang, China, earthquake: A volcano-related fluid-driven earthquake?

摘要

A high-resolution tomographic model inferred from local and teleseismic arrival-time data under Yunnan, southwest China, shows that the 2011 Yingjiang earthquake (M 5.8) occurred around a low-velocity anomaly that extends down to the top of the mantle transition zone and is attributable to upwelling flow of the active Tengchong volcano. Fluids in the flow may mainly originate from the dehydration of the eastward subduction of the Indian plate in the mantle transition zone and have reached the fault zone. Our results suggest that the occurrence of the Yingjiang earthquake could be closely related to fluids that might enhance the stress concentration on the seismogenic layer, as well as decrease the effective normal stress across the fault planes of the Da Yingjiang fault. We conclude that the Yingjiang earthquake might be a volcano-related fluid-driven earthquake. The successive occurrence of small earthquakes (M > 4:0) and the Yingjiang aftershocks may imply recent magmatism at the Tengchong volcano. The 4 February 2011 Indo-Burma earthquake (M 6.4) occurred at ～90 km depth, suggesting that the Indian plate is still active and currently subducting eastward, which may explain why several moderate-large earthquakes, such as the 24 March 2011 Burma earthquake (M 7.2), have occurred recently in the region.