Slidequakes associated with deformation of the Xishancun soil landslide in southwest China
Abstract
Slidequakes are seismic events recorded at creeping landslides, which is usually related to sudden releases of seismic energy caused by interactions between the landslide material and the bedrock and/or along lateral boundary faults, internal fractures, and local collapses at the surface. Slidequakes provides key deformation characteristics of the landslide movement, which is supplementary to aseismic rheologic deformation. In this study, we deployed 50 short-period and 10 broadband seismometers on the Xishancun Landslide in southwestern China to investigate its deformation. GPS measurements and InSAR imaging show largest displacement rates at the toe of the landslide. A large number of slidequakes are detected and analyzed through seismological techniques. These events can be categorized into four groups of low velocity events (LVEs) and two groups of high velocity events (HVEs), according to their apparent velocities and arrival-time signatures at 60 stations. Particle-motion analysis shows that waveforms of the LVEs are mainly comprised of surface waves, while body waves dominate HVE waveforms. Synthetic tests indicate that the LVEs and HVEs occur near the ground surface and the sliding interface of the landslide, respectively. At the toe of the landslide, some LVEs and HVEs have similar horizontal positions and they are often separated by 5-6 s. LVEs have a more obvious diurnal distribution than HVEs, which indicates that the air temperature might be a factor that controls the landslide surficial deformation. We also determine focal mechanisms for these slidequakes with high signal-to-noise ratios using single force and double couple inversion codes. The results show that the LVEs may be related to the local collapses of the landslide, whose waveforms fit better with single-force mechanisms than with double-couple faulting. The HVEs may originate from the side-bounding strike slipping between the landslide and the transverse ridges, whose waveforms fit better with double-couple faulting than with single-force mechanisms. Our observation and inversion results show abundant seismic deformation in the Xishancun landslide, and locations and focal mechanisms of slidequakes can reveal detail deformation behaviors.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH33E0961S
- Keywords:
-
- 1810 Debris flow and landslides;
- HYDROLOGY;
- 1826 Geomorphology: hillslope;
- HYDROLOGY;
- 4306 Multihazards;
- NATURAL HAZARDS;
- 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGY