Discussion on the latest surface ruptures near the Zhonggu village along the Selaha segment of the Xianshuihe fault zone

Abstract

The Selaha segment of the Xianshuihe fault zone was the seismogenic fault of the 2014 Kangding MS 6.3 earthquake. This segment has been considered as one of the most dangerous areas for surface rupture-induced earthquakes with a magnitude of M≥7 due to the long elapsed time of the latest surface rupture event (the 1725 Kangding MS7.0 earthquake). Obtaining the spatial distribution of the latest seismic surface rupture along the Selaha fault is significant for determining the seismic activity history, assessing the seismic potential, and preventing and mitigating disasters. However, there is still considerable controversy about the extension northwestern of the latest surface rupture. In order to solve this problem, we excavated two large paleoseismic trenches in the Zhonggu village where the previous data believed that there was no coseismic surface rupture, and obtained the rupture history of this region. The latest event (E6) occurred after A.D.746±51. Based on the trench profile evidence, geomorphological features, and historical earthquake records, the latest event E6 is associated with the 1725 Kangding MS7.0 earthquake, indicating that the surface rupture of the event E6 has extended to at least the Zhonggu village.

Keywords

• the xianshuihe fault
• the selaha segment
• earthquake-induced surface rupture
• trench
• the 2014 kangding ms6.3 earthquake