Assessment of risks of loose landslide deposits formed by the 2008 Wenchuan earthquake

Abstract. A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 × 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

[1]  Garth Powell,et al.  Discussion 'Landslide Risk Management Concepts and Guidelines' , 2002 .

[2]  Kyoji Sassa,et al.  Landslide risk evaluation and hazard zoning for rapid and long-travel landslides in urban development areas , 2004 .

[3]  P. Finlay,et al.  Landslide risk assessment: prediction of travel distance , 1999 .

[4]  J. Zhang,et al.  Stability analysis of rainfall-induced slope failure: a review , 2011 .

[5]  F. Legros.  The mobility of long-runout landslides , 2002 .

[6]  Robin Fell,et al.  Travel distance angle for "rapid" landslides in constructed and natural soil slopes , 2003 .

[7]  Robin Fell,et al.  Landslide risk assessment : proceedings of the International Workshop on Landslide Risk Assessment, Honolulu, Hawaii, USA, 19-21 February 1997 , 1997 .

[8]  Simone Frigerio,et al.  Landslide risk analysis: a multi-disciplinary methodological approach , 2007 .

[9]  L. Cascini.  Applicability of landslide susceptibility and hazard zoning at different scales , 2008 .

[10]  Y. Xu,et al.  Field testing of erodibility of two landslide dams triggered by the 12 May Wenchuan earthquake , 2011 .

[11]  Harianto Rahardjo,et al.  SHEAR-STRENGTH CHARACTERISTICS OF A RESIDUAL SOIL , 1995 .

[12]  L. Zhang.  Challenges in multi-hazard risk assessment and management: Geohazard chain in Beichuan Town caused by Great Wenchuan Earthquake , 2009 .

[13]  David Parkinson,et al.  Risk: Analysis, perception and management. report of a Royal Society Study Group: Pp 201. The Royal Society. 1992. Paperback £15.50 ISBN 0 85403 467 6 , 1993 .

[14]  W. Tang,et al.  Development of a Risk-Based Landslide Warning System , 2011 .

[15]  R. Fell.  Landslide risk assessment and acceptable risk , 1994 .

[16]  W. Z. Savage,et al.  Guidelines for landslide susceptibility, hazard and risk zoning for land-use planning , 2008 .

[17]  Jordi Corominas,et al.  The angle of reach as a mobility index for small and large landslides , 1996 .

[18]  Fausto Guzzetti,et al.  Societal landslide and flood risk in Italy. , 2010 .

[19]  Wilson H. Tang,et al.  Probability Concepts in Engineering: Emphasis on Applications to Civil and Environmental Engineering , 2006 .

[20]  D. G. Fredlund,et al.  Wetting front advancing column test for measuring unsaturated hydraulic conductivity , 2009 .

[21]  M. Sorriso-Valvo,et al.  Geomorphic controls of the shape and mobility of rock avalanches , 1991 .

[22]  L. Zhang,et al.  Development of a Modified Axis Translation Technique for Measuring SWCCs for Gravel Soils at Very Low Suctions , 2009 .

[23]  Li Min Zhang,et al.  Particle flow and segregation in a giant landslide event triggered by the 2008 Wenchuan earthquake, Sichuan, China , 2011 .

[24]  Li Min Zhang,et al.  RAINFALL-INDUCED SLOPE FAILURE CONSIDERING VARIABILITY OF SOIL PROPERTIES , 2005 .

[25]  P. Peduzzi,et al.  Global landslide and avalanche hotspots , 2006 .

[26]  D. Fredlund,et al.  Equations for the soil-water characteristic curve , 1994 .