Spatiotemporal sequence of Himalayan debris flow from analysis of high-frequency seismic noise

[1] During the 2003 summer monsoon, the Hi-CLIMB seismological stations deployed across the Himalayan Range detected bursts of high-frequency seismic noise that lasted several hours to days. On the basis of the cross correlation of seismic envelopes recorded at 11 stations, we show that the largest transient event on 15 August was located nearby a village partially destroyed on that day by a devastating debris flow. This consistency in both space and time suggests that high-frequency seismic noise analysis can be used to monitor debris flow generation as well as the evacuation of the sediment. A systematic study of one year of seismic noise, focusing on the detection of similar events, provides information on the spatial and temporal occurrence of mass movements at the front of the Himalayas. With a 50% probability of occurrence of a daily event, a total of 46 debris flows are seismically detected. Most of them were generated in regions of steep slopes, large gullies, and loose soils during the 2003 summer monsoon storms. These events are compared to local meteorological data to determine rainfall thresholds for slope failures, including the cumulative rainfall needed to bring the soil moisture content to failure capacity. The inferred thresholds are consistent with previous estimates deduced from soil studies as well as sediment supply investigations in the area. These results point out the potential of using seismic noise as a dedicated tool for monitoring the spatiotemporal occurrence of landslides and debris flows on a regional scale.

[1]  Richard M. Iverson,et al.  Debris-flow mobilization from landslides , 1997 .

[2]  M. G. Angeli,et al.  A critical review of landslide monitoring experiences , 2000 .

[3]  Chen Chen-lung,et al.  DEBRIS-FLOW HAZARDS MITIGATION: MECHANICS, PREDICTION, AND ASSESSMENT , 2007 .

[4]  R. Dahal,et al.  Causes of large-scale landslides in the Lesser Himalaya of central Nepal , 2009 .

[5]  Olav Slaymaker,et al.  Landslide inventory in a rugged forested watershed: a comparison between air-photo and field survey data , 2003 .

[6]  S. K. Bartarya,et al.  Catastrophic mass movement of 1998 monsoons at Malpa in Kali Valley, Kumaun Himalaya (India) , 2000 .

[7]  B. Pratt-Sitaula,et al.  Rainfall thresholds for landsliding in the Himalayas of Nepal , 2004 .

[8]  Jérôme Lavé,et al.  Fluvial incision and tectonic uplift across the Himalayas of central Nepal , 2001 .

[9]  A. Walden,et al.  Spectral analysis for physical applications : multitaper and conventional univariate techniques , 1996 .

[10]  M. Arattano,et al.  Ten years of debris-flow monitoring in the Moscardo Torrent (Italian Alps) , 2002 .

[11]  R. Marston,et al.  Geoecology and mass movement in the Manaslu-Ganesh and Langtang-Jugal Himals, Nepal , 1998 .

[12]  L. Reid.  Calculation of average landslide frequency using climatic records , 1998 .

[13]  G. Tartari,et al.  Meteorological observations at high altitude in the Khumbu Valley, Nepal Himalayas, 1994-1999 , 2002 .

[14]  B. Pratt-Sitaula,et al.  Modern erosion rates in the High Himalayas of Nepal , 2008 .

[15]  John Chen,et al.  Underplating in the Himalaya-Tibet Collision Zone Revealed by the Hi-CLIMB Experiment , 2009, Science.

[16]  Yasumasa Itakura,et al.  A debris-flow monitoring devices and methods bibliography , 2005 .

[17]  D. Thomson,et al.  Spectrum estimation and harmonic analysis , 1982, Proceedings of the IEEE.

[18]  Olivier Maquaire,et al.  The use of Global Positioning System techniques for the continuous monitoring of landslides: application to the Super-Sauze earthflow (Alpes-de-Haute-Provence, France) , 2002 .

[19]  D. P. Adhikari,et al.  Debris flow disaster at Larcha, upper Bhotekoshi Valley, central Nepal , 2005 .

[20]  A. Barros,et al.  A study of the 1999 monsoon rainfall in a mountainous region in central Nepal using TRMM products and rain gauge observations , 2000 .

[21]  Jerome Vergne,et al.  Spectral analysis of seismic noise induced by rivers: A new tool to monitor spatiotemporal changes in stream hydrodynamics , 2008 .

[22]  A. Shields,et al.  Anwendung der Aehnlichkeitsmechanik und der Turbulenzforschung auf die Geschiebebewegung , 1936 .

[23]  Ching Jer Huang,et al.  Ground vibrations produced by rock motions and debris flows , 2007 .

[24]  J. Lavé,et al.  Changes of bedload characteristics along the Marsyandi River (central Nepal): Implications for understanding hillslope sediment supply, sediment load evolution along fluvial networks, and denudation in active orogenic belts , 2006 .

[25]  R. Dahal,et al.  Representative Rainfall thresholds for landslides in the Nepal Himalaya , 2008 .

[26]  Nicholas Brozovic,et al.  Bedrock incision, rock uplift and threshold hillslopes in the northwestern Himalayas , 1996, Nature.

[27]  B. N. Upreti,et al.  An overview of the stratigraphy and tectonics of the Nepal Himalaya , 1999 .

[28]  N. Hovius,et al.  Supply and Removal of Sediment in a Landslide‐Dominated Mountain Belt: Central Range, Taiwan , 2000, The Journal of Geology.

[29]  G. Hetényi.  Evolution of deformation of the Himalayan prism: from imaging to modelling , 2007 .

[30]  J. Shroder.  Slope failure and denudation in the western Himalaya , 1998 .

[31]  B. Bookhagen,et al.  Bedrock channel geometry along an orographic rainfall gradient in the upper Marsyandi River valley in central Nepal , 2007 .

[32]  D. Varnes.  SLOPE MOVEMENT TYPES AND PROCESSES , 1978 .

[33]  Lorenzo Marchi,et al.  Systems and Sensors for Debris-flow Monitoring and Warning , 2008, Sensors.

[34]  K. Ueno.  Meteorological observations during 1994-2000 at the Automatic Weather Station (GEN-AWS) in Khumbu region, Nepal Himalayas , 2001 .