Deformation of the Xishancun Landslide, Sichuan, inferred from seismicity

Risheng Chu

Published August 15, 2016, SCEC Contribution #7045, 2016 SCEC Annual Meeting Poster #260

Unstability of landslides, e. g. the slope movement and the internal fracturing of the rock mass, can often generate microseismicity, which is recorded as seismic signals on seismographs. The temporal and spatial distribution of the unstable regions is key to understanding the deformation of the landslides and provides important information for landslide early warning, which can be used as a supplementary to geodetic monitoring of landslide surface. Toward this end, we deployed 30 seismometers on Xishancun landslide with a station spacing of 200~500 meters between the August and November of 2015. The Xishancun landslide is about 80 million cubic meters and located about 60 km northwest of the hypocenter of the 2008 Wenchuan earthquake. The landslide keeps deforming at about 5~8 cm/year after the earthquake, which poses great hazards. Based on travel time and waveform characteristics, we found many seismic events associated with the landslide and used their waveform envelopes as templates. We then applied the sliding-window cross-correlation technique to detect about 100 more events. About 80% of the events are located on the foot of the landslide while the others located on the head. The head and foot of the landslide accumulate considerable deformation that radiated seismic energy could be recorded by all stations. In addition, there are many smaller events occurred in the main body of the landslide whose released less energy can only be recorded by a few stations. The distribution of the seismic events may be related to the internal fractures and movement of the landslide, which agrees with deformed areas monitored by geodetic methods.

Key Words
Landslide, microseismicity

Citation
Chu, R. (2016, 08). Deformation of the Xishancun Landslide, Sichuan, inferred from seismicity. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology