Ambient noise and ERT data provide insights into the structure of co-seismic rock avalanche deposits in Sichuan (China)

Abstract The post-seismic history of the 2008 Mw7.9 Wenchuan earthquake shows that marginally stable deposits large co-seismic landslide dams can pose persistent debris flow hazards for downstream areas. Here, we combine analyses single-station recordings ambient noise with electrical resistivity tomography (ERT) surveys to explore potential drawing information on structure and geometry deposit a rock avalanche triggered by Mw 7.9 earthquake, which dammed Yangjia stream in Sichuan Province (China). substantial thickness heterogeneity this kind limit application standard geophysical techniques, like active seismic surveys, require highly energetic sources long linear geophone arrays reach adequate investigation depths. Passive methods, relying determine site resonance properties, controlled contrast between soft surface layers stiffer substratum, offer opportunity investigating subsoil properties down larger In particular, use recently developed technique, isolates contribution Rayleigh waves draws sub-soil from inversion wave ellipticity curves plotted as function frequency. framework, ERT data support curve inversion, typically affected non-univocal solutions, providing constraints defining uppermost surficial layers. results allowed inferring overlap different within deposit, well estimating lateral variations their S-wave (Vs) velocities.