References

NHESS

Natural Hazards and Earth System Sciences

NHESS

Nat. Hazards Earth Syst. Sci.

1684-9981

Copernicus Publications

Göttingen, Germany

10.5194/nhess-12-3545-2012

Seismic monitoring of precursory fracture signals from a destructive rockfall in the Vorarlberg Alps, Austria

Walter

¹ Schwaderer

¹ Joswig

Institute for Geophysics, University of Stuttgart, 70174 Stuttgart, Germany

29 11 2012

12 11 3545 3555

2012

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In this study we describe the seismic analysis of precursory patterns of a rockfall in the "Rappenlochschlucht", a gorge located in the Vorarlberg Alps, Austria. The rockfall with an estimated volume of 15 000 m3 occurred on 10 May 2011 (10:48:43 UTC) and destroyed a massive bridge construction. Fortunately, the rockfall did not cause any casualties. A permanent seismic network consisting of three seismic small arrays was installed in July 2009 in 5 km distance to the gorge, at the Heumoes slope, in order to detect and locate slope-related fracture processes within a radius of a few hundred meters. By chance, the rockfall with an estimated equivalent local magnitude of ML,eq = 2.3 was recorded by the seismic network. We observed several smaller rockfall events up to three hours, and 12 fracture signals up to five hours prior to the rockfall. The smaller rockfalls and the fractures were both located in the vicinity of the source area where the main event emerged, applying absolute and relative localization methods. These specific types of fracture signals located near by the gorge "Rappenlochschlucht" have never been observed in almost two years of permanent seismic monitoring. We interpret these fractures with magnitudes between ML = 0.4 and −0.5 as precursory signals of the main rockfall event. The observed fractures and the weaker rockfalls are sequences of initial stress relief within the rock mass and mass transferring processes, respectively, finally causing the destructive main rockfall event. To investigate possible triggers of the destructive rockfall event, several meteorological and hydrological data as well as the local seismicity during that period of time were analyzed and discussed in detail in this study. Unfortunately, no triggering factor of the rockfall event was identified, and remains therefore unknown.

References 1

Beniston, M.: August 2005 intense rainfall event in Switzerland: Not necessarily an anolog for strong convective events in a greenhouse climate, Geophys. Res. Lett., 33, L05701, <a href="http://dx.doi.org/10.1029/2005GL025573">https://doi.org/10.1029/2005GL025573</a>, 2006.

Brückl, E. and Mertl, S.: Seismic Monitoring of Deep-Seated Mass Movements, Proc. of INTERPRAEVENT International Symposium "Disaster Mitigation of Debris Flows, Slope Failures and Landslides", Universal Academy Press, Inc., Tokyo, Japan, 571–580, 2006.

Deichmann, N. and Giardini, D.: Earthquakes induced by the stimulation of an enhanced geothermaö system below Basel (Switzerland), Seis. Res. Lett., 80, 784–798, 2009.

Depenthal, C. and Schmitt, G.: Monitoring of a landslide in Vorarlberg/Austria, in: Proc. Int. FIG Symp. on Deformation Measurements, 11th, Santorini (Thera) Island, Greece, 25–28 May 2003, edited by: Stiros, S. and Pytharouli, S., Geodesy and Geodetic Appl. Lab., Dep. of Civ. Eng., Patras Univ., Rio, Greece, 289–295, 2003.

Fierz, C. and Lehning, M.: Assessment of the microstructure-based snow-cover model SNOWPACK: thermal and mechanical properties, Cold Reg. Sci. Technol., 33, 123–131, 2001.

Gomberg, J., Bodin, P., Savage, W., and Jackson, M. E.: Landslide faults and tectonic faults, analogs?: The Slumgullion earthflow, Colorado, Geology, 23, 41–44, 1995.

Gomberg, J., Schulz, W., Bodin, P., and Kean, J.: Seismic and geodetic signatures of fault slip at the Slumgullion Landslide Natural Laboratory, J. Geophys. Res., 116, B09404, <a href="http://dx.doi.org/10.1029/2011JB008304">https://doi.org/10.1029/2011JB008304</a>, 2011.

Got, J.-L., Mourot, P., and Grangeon, J.: Pre-failure behaviour of an unstable limestone cliff from displacement and seismic data, Nat. Hazards Earth Syst. Sci., 10, 819–829, <a href="http://dx.doi.org/10.5194/nhess-10-819-2010">https://doi.org/10.5194/nhess-10-819-2010</a>, 2010.

Gruber, S. and Haeberli, W.: Permafrost in steep bedrock slopes and its temperature-related destabilization following climate change, J. Geophys. Res., 112, 1–10, <a href="http://dx.doi.org/10.1029/2006JF000547">https://doi.org/10.1029/2006JF000547</a>, 2007.

Häge, M. and Joswig, M.: Untersuchung der Lokalisierungsgenauigkeit von Kleinarrays anhand induzierter Seismizität während der Stimulationsphase des Deep-Heat-Mining-Projektes in Basel, DGG Mitteilungen 1/2011, 24–30, 2011.

Hainzl, S., Kraft, T., Wassermann, J., Igel, H., and Schmedes, E.: Evidence for rainfall-triggered earthquake activity, Geophys. J. Int., 33, L19303, <a href="http://dx.doi.org/10.1029/2006GL027642">https://doi.org/10.1029/2006GL027642</a>, 2006.

Hanson, S. and Hoelzle, M.: The thermal regime of the active layer at the Murtèl rock glacier based on data from 2002, Permafrost Periglac. Process., 15, 273–282, 2004.

Harris, C., Arenson, L. U., Christiansen, H. H., Etzelmüller, B., Frauenfelder, R., Gruber, S., Haeberli, W., Hauck, C., Hölzle, M., Humlum, O., Isaksen, K., Kääb, A., Kern-Lütschg, M. A., Lehning, M., Matsuoka, N., Murton, J. B., Nötzli, J., Phillips, M., Ross, N., Seppälä, M., Springman, S. M., and Vonder Mühll, D.: Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnical responses, Earth-Sci. Rev., 92, 117–171, <a href="http://dx.doi.org/10.1016/j.earscirev.2008.12.002">https://doi.org/10.1016/j.earscirev.2008.12.002</a>, 2009.

Helmstetter, A. and Garambois, S.: Seismic monitoring of Séchilienne rockslide (French Alps): Analysis of seismic signals and their correlation with rainfalls, J. Geophys. Res., 15, F03016, <a href="http://dx.doi.org/10.1029/2009JF001532">https://doi.org/10.1029/2009JF001532</a>, 2010.

Husen, S., Bachmann, C., and Giardini, D.: Locally triggered seismicity in the central Swiss Alps following the large rainfall event of August 2005, Geophys. J. Int., 171, 1126–1134, 2007.

Joswig, M.: Nanoseismic Monitoring fills the gap between microseismic networks and passive seismic, First Break, 26, 121–128, 2008.

Kääb, A., Huggel, C., Fischer, L., Guex, S., Paul, F., Roer, I., Salzmann, N., Schlaefli, S., Schmutz, K., Schneider, D., Strozzi, T., and Weidmann, Y.: Remote sensing of glacier- and permafrost-related hazards in high mountains: an overview, Nat. Hazards Earth Syst. Sci., 5, 527–554, <a href="http://dx.doi.org/10.5194/nhess-5-527-2005">https://doi.org/10.5194/nhess-5-527-2005</a>, 2005.

Kahn, D.: Hydro-Fractured Reservoirs: A Study using Double-Difference Location Techniques, PhD-thesis, Duke University, 2008.

Keller, F. and Gubler, H. U.: Interaction between snow cover and high mountain permafrost at Murtèl/Corvatsch, Swiss Alps, The 6th International Conference on Permafrost, Beijing, China, 332–337, 1993.

Kennett, B. L. N. and Engdahl, E. R.: Traveltimes for global earthquake location and phase identification, Geophys. J. Int., 105, 429–465, 1991.

Khazai, B. and Sitar, N.: Evaluation of factors controlling earthquake-induced landslides caused by Chi-Chi earthquake and comparison with the Northridge and Loma Prieta events, Eng. Geol., 71, 79–95, 2004.

Levy, C., Baillet, L., Jongmans, D., Mourot, P., and Hantz, D.: The dynamic response of the chamousset rock column (Western Alps, France) before its collapse, J. Geophys. Res., 115, F04043, <a href="http://dx.doi.org/10.1029/2009JF001606">https://doi.org/10.1029/2009JF001606</a>, 2010.

Levy, C., Jongmans, D., and Baillet, L.: Analysis of seismic signals recorded on a prone-to-fall rock column (Vercors massif, French Alps), Geophys. J. Int., 186, 296–310, <a href="http://dx.doi.org/10.1111/j.1365-246X.2011.05046.x">https://doi.org/10.1111/j.1365-246X.2011.05046.x</a>, 2011.

Lindenmaier, F., Zehe, E., Dittfurth, A., and Ihringer, J.: Process identification at a slow-moving landslide in the Vorarlberg Alps, Hydrol. Process., 19, 1635–1651, 2005.

Luetschg, M. A. and Haeberli, W.: Permafrost evolution in the Swiss Alps in a changing climate and the role of the snowcover, Nor. J. Geogr., 59, 77–83, 2005.

Malet, J.-P., van Asch, Th. W. J., van Beek, R., and Maquaire, O.: Forecasting the behaviour of complex landslides with a spatially distributed hydrological model, Nat. Hazards Earth Syst. Sci., 5, 71–85, <a href="http://dx.doi.org/10.5194/nhess-5-71-2005">https://doi.org/10.5194/nhess-5-71-2005</a>, 2005.

Matsuoka, N.: Diurnal freeze-thaw depth in rockwalls: field measurements and theoretical considerations, Earth Surf. Proc. Landf., 19, 423–435, 1994.

Matsuoka, N. and Sakai, H.: Rockfall activity from an alpine cliff during thawing periods, Geomorphology, 28, 309–328, 1999.

Mellor, M.: Engineering properties of snow, J. Glaciol., 19, 15–66, 1977.

Oberhauser, R.: Der geologische Aufbau Österreichs, Springer-Verlag, Wien, 1980.

Prick, A.: Frost weathering and rock fall in an arctic environment, Longyearbyen, Svalbard, available at: <a href="http://research.iarc.uaf.edu/NICOP/DVD/ICOP 2003 Permafrost/Pdf/Chapter_159.pdf">http://research.iarc.uaf.edu/NICOP/DVD/ICOP 2003 Permafrost/Pdf/Chapter_159.pdf</a> (latest access: 3 November 2012), 2003.

Rapp, A.: Recent development of mountain slopes in Kärkevagge and surroundings, Northern Scandinavia, Geogr. Ann., 42, 65–200, 1960.

Roth, M., Dietrich, M., Blikra, L. H., and Lecomte, I.: Seismic monitoring of the unstable rock slope at Åknes, Norway, NORSAR, Report for the International Centre for Geohazards, 2005.

Schulz, W. H., Kean, J. W., and Wang, G.: Landslide movement in southwest Colorado triggered by atmospheric tides, Nat. Geosci., 2, 863–866, <a href="http://dx.doi.org/10.1038/ngeo659">https://doi.org/10.1038/ngeo659</a>, 2009.

Spillmann, T., Maurer, H., Green, A. G., Heincke, B., Willenberg, H., and Husen, S.: Microseismic investigations of an unstable mountain slope in the Swiss Alps, J. Geophys. Res., 112, B07301, <a href="http://dx.doi.org/10.1029/2006JB004723">https://doi.org/10.1029/2006JB004723</a>, 2007.

Stoffel, M., Lièvre, I., Conus, D., Grichting, M. A., Raetzo, H., Gärtner, H. W., and Monbaron, M.: 400 years of debris-flow activity and triggering weather conditions: Ritigraben, Valais, Switzerland, Arct., Antarc., Alp. Res., 37, 387–395, 2005.

Sturm, M., Holmgren, J., König, M., and Morris, K.: The thermal conductivity of seasonal snow, J. Glaciol., 43, 26–41, 1997.

Travelletti, J., Oppikofer, T., Delacourt, C., Malet, J.-P., and Jaboyedoff, M.: Monitoring landslides displacements during a controlled rain experiment using a long-range terrestrial laser scanning (TLS), The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. XXXVII, Part B5, 485–490, 2008.

Tsaparas, I., Rahardjo, H., Toll, D. G., and Leong, E. C.: Controlling parameters for rainfall-induced Landslides, Comput. Geosci., 29, 1–27, 2002.

van Asch, T. W. J., Buma, J., and van Beek, L. P. H.: A view on some hydrological triggering systems in landslides, Geomorphology, 30, 25–32, 1999.

Walter, M. and Joswig, M.: Seismic monitoring of fracture processes generated by a creeping landslide in the Vorarlberg Alps, First Break, 26, 131–135, 2008.

Walter, M. and Joswig, M.: Seismic characterization of slope dynamics caused by softrock-landslides: The Super-Sauze case study, in: Proceedings of the International Conference on Landslide Processes: from geomorphologic mapping to dynamic modelling, edited by: Malet, J.-P., Remaître, A., and Boogard, T., Strasbourg, CERG Editions, 215–220, 2009.

Walter, M., Niethammer, U., Rothmund, S., and Joswig, M.: Joint analysis of the Super-Sauze (French Alps) mudslide by nanoseismic monitoring and UAV-based remote sensing, First Break, 27, 75–82, 2009.

Walter, M., Walser, M., and Joswig, M.: Mapping Rainfall-Triggered Slidequakes and Seismic Landslide-Volume Estimation at Heumoes slope, Vadose Zone J., 10, 487–495, 2011.

Walter, M., Arnhardt, C., and Joswig, M.: Seismic monitoring of rockfalls, slide quakes, and fissure development at the Super-Sauze mudslide, French Alps, Eng. Geol., 128, 12–22, 2012.

Wienhöfer, J., Lindenmaier, F., and Zehe, E.: Challenges in Understanding the Hydrologic Controls on the Mobility of Slow-Moving Landslides, Vadose Zone J., 10, 496–511, 2011.

Wust-Bloch, H. and Joswig, M.: Pre-collapse identification of sinkholes in unconsolidated media at Dead Sea area by "nanoseismic monitoring" (graphical jackknife location of weak sources by few, low-SNR records), Geophys. J. Int., 167, 1220–1232, 2006.

Zhang, T.: Influence of the seasonal snow cover on the ground thermal regime: an overview, Rev. Geophys., 43, RG4002, <a href="http://dx.doi.org/10.1029/2004RG000157">https://doi.org/10.1029/2004RG000157</a>, 2005.