Linking Sub-surface Slidequakes to Superficial Fissure Growth and Displacement Analysis: The Super-Sauze Mudslide Field Campaign 2010
Applying passive seismic analysis techniques realized by Nanoseismic Monitoring at creeping to slow-moving, soft-rock landslides in the Alps, we observed fracture processes of slope material, also called slidequakes. Their time-frequency signature resembles impulsive signals from local earthquakes, and indicates brittle fracturing of slope material. We could locate slidequakes within tens to hundreds meters off our stations, and determine Ml between −3 and −1. Slidequakes are very weak signals with poor signal-to-noise ratio (SNR); thus neither precise depths nor moment tensor solutions could be derived. At Super-Sauze two further event types were observed (I) caused by rockfall impacts, and (II) resembling non-impulsive, reverberant ETS (episodic tremor and slip) signals of volcanic and lower crust seismology. Type (II) is eventually linked to embedded rocks scratching along in situ crests, or to fissure opening at surface. A comprehensive field campaign was conducted from spring to summer 2010 to observe how these fractures relate to slope movement, fissure development and hydro-meteorological changes. Geophysical, hydrological, geodetic, and geotechnical monitoring was performed, complemented by daily soil sampling and UAV-based (unmanned aerial vehicle) photogrammetric data acquisition. First processing results help to evaluate on different theories of fracture generation.
KeywordsLandslide Nanoseismic monitoring Slidequakes
We thank OMIV project (Observatoire des Instabilités de Versants), and Jean-Philippe Malet (EOST, University of Strasbourg, France) for support in the field and providing datasets. The work is funded by DFG project JO 400/5-1.
- Ibele T (2011) Tectonics of the western Swiss Molasse Basin during Cenozoic time. Ph.D. thesis, University Fribourg, Geofocus, vol 27, p 166Google Scholar
- Joswig M (2008) Nanoseismic monitoring fills the gap between microseimic networks and passive seismic. First Break 26:121–128Google Scholar
- Jurich DM, Miller RJ (1987) Acoustic monitoring of landslides. Transportation research record. Geotechnology 1119:30–38Google Scholar
- Koerner RM, Lord AE, McCabe WM (1977) Acoustic-emission behavior of cohesive soils. J Geotech Eng Div—ASCE 103:837–850Google Scholar
- Sick B, Walter M, Joswig M (2013) Near-surface fracture and impact discovery from landslides and sinkholes by sonogram screening. First Break 31:95–101Google Scholar
- Walter M, Joswig M (2011) Resolving landslide-bedrock interaction by nanoseismic monitoring. In: Catani F, Margottini C, Trigila A, Iadanza C (eds) Proceedings of the 2nd world landslide forum, Rome, 3–7 Oct 2011Google Scholar
- Wells DL, Coppersmith KJ (1994) New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement. Bull Seismol Soc Am 84(4):974–1002Google Scholar