Comprehensive mapping of landslide dynamics by nanoseismic monitoring

Abstract

Marco Walter and Manfred Joswig present the mapping of key dynamics influencing deepseated mass movements by applying nanoseismic monitoring at a mudslide in the French Alps. Slope-related failure by fracture processes with magnitudes of ML < 0.0 has been observed on rockslides by classical seismological monitoring techniques. Fracture signals at rockslides were monitored by e.g,. Roth et al. (2005) at the Aknes fjord in Norway, Brückl and Mertl (2006) in the Austrian Alps, Spillmann et al. (2007), in the Swiss Alps, for a rockslide by Helmstetter and Garambois (2010), and for a detaching rock column by Levy et al. (2011), both in the French Alps. In contrast to the aforementioned studies, we present the seismic analysis of softrock-landslide dynamics observed at the mudslide in Super-Sauze, French Alps (Walter et al., 2009, 2012). Like Super-Sauze, most softrock landslides are geomorphically classified as creeping, thus the existence of measurable signals caused by brittle deformation could not have been expected. The apparent contradiction of viscous creep coexisting with brittle deformation on softrock landslides resembles crustal-scale tectonics where aseismic creep coexists with earthquakes (Peng and Gomberg, 2010). Already in 1995, Gomberg et al. proposed the term ‘slidequake’, which describes the fracturing or stress relief of slope material by means of brittle failure.