NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-10-831-2010 Microseismic activity analysis for the study of the rupture mechanisms in unstable rock masses Amitrano D. 1 Arattano M. 2 Chiarle M. 2 Mortara G. 2 Occhiena C. 3 Pirulli M. 3 Scavia C. 3 LGIT, UMR5559, CNRS-Université Joseph Fourier, Grenoble, France CNR-IRPI, Torino, Italy Department of Structural and Geotechnical Engineering, Politecnico di Torino, Italy 15 04 2010 10 4 831 841 Copyright: © 2010 D. Amitrano et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/10/831/2010/nhess-10-831-2010.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/10/831/2010/nhess-10-831-2010.pdf

Rockfalls are common instabilities in alpine areas and can cause significant damage. Since high mountains have been affected by an increasing number of these phenomena in the last years, a possible correlation with permafrost degradation induced by climate change has been hypothesized. <br><br> To investigate this topic, a monitoring system, made of 5 triaxial geophones and 1 thermometer, was installed in 2007 at the Carrel hut (3829 m a.s.l., Matterhorn, North-western Alps), in the frame of the Interreg IIIA Alcotra project n. 196 "Permadataroc". <br><br> The preliminary data processing relates to the classification of recorded signals, the identification of the significant microseismic events and the analysis of their distribution in time and space. The first results indicated a possible correlation between clusters of events and temperature trend, and a concentration of events in specific sectors of the rock mass. <br><br> Research is still in progress. The recording of data for a longer period is planned to fully understand seasonal trends and spatial distribution of microseismic activity, and possible relations with permafrost degradation. Nevertheless, the preliminary observations prove that the monitoring system can detect noises generated by rock slope deformation. Once fully developed, this technique could become a helpful tool for early warning and preliminary stability assessments.

 References Amitrano, D., Grasso, J. R., and Senfaute, G.: Seismic precursory patterns before a cliff collapse and critical-point phenomena, Geoph. Res. Let., 32(8), L08314, https://doi.org/10.1029/2004GL022270, 2005. Amitrano, D., Gaffet, S., Malet, J.-P., and Maquaire, O.: Understanding mudslides through micro-seismic monitoring: The Super-Sauze (South French Alps) case study, B. Soc. Geol. Fr., 178(2), 149–157; https://doi.org/10.2113/gssgfbull.178.2.149, 2007. Chiarle, M. and Mortara, G.: Geomorphological impact of climate change on alpine glacial and periglacial areas. Examples of processes and description of research needs, in: Proceedings 11th Interpraevent Congress 2008 "Protection of populated territories from floods, debris flows, mass movements and avalanches", Dornbirn, Austria, 2, 111–122, 26–30 Mai 2008. Collison, A., Wade, S., Griffiths, J., and Dehn, M.: Modelling the impact of predicted climate change on landslide frequency and magnitude in SE England, Eng. Geol., 55(3), 205–218, 2000. Dixon, N., Hill, R., and Kavanagh, J.: Acoustic emission monitoring of slope instability: development of an active waveguide system, Geotechnical Engineering, 156(2), 83–95, 2003. Dixon, N., Kavanagh, J., and Hill, R.: Monitoring landslide activity and hazard by acoustic emssion, J. Geol. Soc. China, 39(4), 437–464, 1996. Eberhardt, E., Spillmann, T., Maurer, H., Willenberg, H., Loew, S., and Stead, D.: The Randa Rockslide Laboratory: Establishing brittle and ductile instability mechanisms using numerical modelling and microseismicity, Proceedings of the 9th International Symposium of Landslides, Rio de Janeiro, Brazil, 481–487, 2004. Evans, A. G.: Acoustic emission sources in brittle solids, in: Fundamentals of acoustic emission, edited by: Ono, K., University of California, Los Angeles, 209–227, 1979. Evans, S. G. and Clague, J. J.: Recent climatic change and catastrophic geomorphic processes in mountain environments, Geomorphology, 10, 107–12, 1994. Fischer L., Kääb A., Huggel C. and Noetzli J.: Geology, glacier retreat and permafrost degradation as controlling factors of slope instabilities in a high-mountain rock wall: the Monte Rosa east face, Nat. Hazards Earth Syst. Sci., 6, 761–772, 2006. Gruber, S., Hoelzle, M., and Haeberli, W.: Permafrost thaw and destabilization of Alpine rock walls in the hot summer of 2003, Geophys. Res. Lett., 31, L13504, https://doi.org/10.1029/2004GL020051, 2004. Gruber, S. and Haeberly, W.: Permafrost in steep bedrock slopes and its temperature related destabilization following climate change, J. Geophys. Res., 112, F02S18, https://doi.org/ 10.1029/2006-JF000547, 2007 Gruner, U.: Climatic and meteorological influences on rockfall and rockslides, in: Proceedings 11th Interpraevent Congress 2008 "Protection of populated territories from floods, debris flows, mass movements and avalanches", Dornbirn, Austria, 2, 147–158, 26–30&nbsp;Mai&nbsp;2008. Hardy, H. R. and Kimble, E. J.: Application of high-frequency AE/MS techniques to rock slope monitoring, in: Proceedings Fifth Conference on Acoustic Emission/Microseismic Activity in Geologic Structures and Materials, Pennsylvania State University, Trans Tech Publications, Clausthal, Germany, 1991 Hardy, H. R.: Acoustic emission/microseismic activity – Principles, Techniques and Geotechnical Applications, A.A.&nbsp;Balkema, Lisse, Netherlands, 2003. Huggel, C.: Recent extreme slope failures in glacial environments: effects of thermal perturbation. Quaternary Sci. Rev., 28(11–12), 1119–1130, 2009. Jaedicke, C., Solheim, A., Blikra, L. H., Stalsberg, K., Sorteberg, A., Aaheim, A., Kronholm, K., Vikhamar-Schuler, D., Isaksen, K., Sletten, K., Kristensen, K., Barstad, I., Melchiorre, C., Høydal, Ø. A., and Mestl, H.: Spatial and temporal variations of Norwegian geohazards in a changing climate, the GeoExtreme Project, Nat. Hazards Earth Syst. Sci., 8, 893–904, 2008. Jakob, M. and Lambert, S.: Climate change effects on landslides along the southwest coast of British Columbia, Geomorphology, 107, 275–284, https://doi.org/10.1016/j.geomorph.2008.12.009, 2009. Jomelli, V., Brunstein, D., Grancher, D., and Pech, P.: Is the response of hill slope debris flows to recent climate change univocal? A case study in the Massif des Ecrins (French Alps), Climatic Change, 85, 119–137, https://doi.org/10.1007/s10584-006-9209-0, 2007. Kennedy, B. A. and Niermeyer, K. E.: Slope Monitoring systems used in the Prediction of a Major Slope Failure at the Chuquicamata Mine, Chile, in: Proc. On Planning Open Pit Mines, Balkema, Johannesburg, South Africa, 1971. Kolesnikov, Yu. I., Nemirovich-Danchenko, M. M., Goldin, S. V., and Seleznev, V. S.: Slope stability monitoring from microseismic field using polarization methodology, Nat. Hazards Earth Syst. Sci., 3, 515–521, 2003. Lockner, D. A.: The role of acoustic emission in the study of rock fracture, Int. J. Rock Mech. Min., 30(7), 883–899, 1993. Nicholson, C.: Recent developments in rockburst and mine seismicity research, in: Rock Mechanics, edited by: Wawersik, T. A., Balkema, Rotterdam, Holland, 1992. Obert, L.: The Microseismic Method: Discovery and Early History, in: Proceeding First Conference on Acoustic Emission/Microseismic Activity in Geologic Structures and Materials, The Pennsylvania State University, Trans Tech Publications, Clausthal, Germany, 1977. Shiotani, T.: Evaluation of long-term stability for rock slope by means of acoustic emission technique, NDT & Int., 39, 217–228, 2006. Signori, M. and Bani, D.: Cervino –- Capanna Carrel. Impianto di monitoraggio per emissioni acustiche, Solgeo s.r.l. Internal Report, Rel.&nbsp;G0304_07, 2007 Willenberg, H., Evans, K. F., Eberhardt, E., Loew, S., Spillmann, T., and Maurer, H.: Geological, geophysical and geotechnical investigations into the internal structure and kinematics of an unstable sliding mass in crystalline rock, Proceedings of the 9th International Symposium of Landslides, Rio de Janeiro, Brazil, 489–494, 2004.