The Cheam rock avalanche, which occurred about 5,000 years ago in the lower Fraser Valley, British Columbia, is the largest known catastrophic landslide in western Canada (175×106 m3). A photo-draped digital elevation model of the rock avalanche reveals two morphologically distinct areas, an eastern area of arcuate hummocky ridges separated by flat-floored depressions and a lower western area with a subdued, gently rolling surface. Debris is up to 30 m thick and consists of rubbly, clast- and matrix-supported diamicton derived from local argillaceous metasedimentary rocks. Failure was probably caused by high pore water pressures on a thrust fault that daylights in the source area. Plastic deformation of sediment beneath the rock avalanche debris suggests that liquefaction occurred due to undrained loading when the debris struck the Cheam terrace. Liquefaction also explains the morphology and travel distance of the western debris lobe. The coincidence of well-sorted sands (the Popkum Series soil) with the rock avalanche debris indicates that significant amounts of water flowed over the surface of the landslide just after it came to rest. Stó:lõ Nation oral history suggests that the debris may have buried a village, causing the first known landslide fatalities in Canada.
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Armstrong JE (1981) Post-Vashon Wisconsin glaciation, Fraser Lowland, British Columbia. Geological Survey of Canada, Bulletin 322
Booth DB, Troost KG, Clague JJ, Waitt RB (2004) The Cordilleran Ice Sheet. In: Gillespie AR, Porter SC, Atwater BF (eds) The Quaternary Period in the United States. Developments in Quaternary Science 1:17–43
Carlson KT (ed) (2001) A Stó: lõ-Coast Salish historical atlas. Douglas and McIntyre Publishing Group, Vancouver
Clague JJ (1981) Late Quaternary geology and geochronology of British Columbia. Part 2: Summary and discussion of radiocarbon-dated Quaternary history. Geological Survey of Canada, Paper 80–35
Clague JJ, Shilts WW (1993) Two landslide-dammed lakes in the Cascade Mountains, southwestern British Columbia. In: Current Research, Part E. Geological Survey of Canada, Paper 93–1E, pp 47–54
Comar VK, Sprout PN, Kelly CC (1962) Soil survey of the Chilliwack map area, lower Fraser Valley. British Columbia Department of Agriculture, Preliminary Report No. 4
Eisbacher GH (1979) Cliff collapse and rock avalanches (sturzstroms) in the Mackenzie Mountains, north-western Canada. Canadian Geotechnical J 16:309–334
Evans SG, Clague JJ, Woodsworth GJ, Hungr O (1989) The Pandemonium Creek rock avalanche, British Columbia. Canadian Geotechnical J 26:427–446
Hallett DJ, Hills LV, Clague JJ (1997) New accelerator mass spectrometry radiocarbon ages for the Mazama tephra layer from Kootenay National Park, British Columbia. Canadian J Earth Sciences 34:1202–1209
Hungr O, Evans SG (2004) Entrainment of debris in rock avalanches; an analysis of a long run-out mechanism. Geol Soc Am 116:1240–1252
Hutchinson JN, Bhandari RK (1971) Undrained loading, a fundamental mechanism of mudflows and other mass movements. Geotechnique 21:353–358
Luttmerding HA, Sprout PN (1967) Soil survey of Agassiz area. British Columbia Department of Agriculture, Preliminary Report No. 8
Mathews WH, McTaggart KC (1969) The Hope Landslide, British Columbia. Proc Geological Assoc of Canada 20:65–75
Mathews WH, McTaggart KC (1978) Hope rockslides, British Columbia. In: Voight B (ed) Rockslides and Avalanches, 1, Natural Phenomena. Elsevier, New York, pp 259–275
Monger JWH (1966) The stratigraphy and the type area of the Chilliwack Group, southwestern British Columbia. Unpublished Ph.D. Thesis, University of British Columbia, Vancouver
Naumann CM (1990) The Cheam Slide: a study of the interrelationship of rock avalanches and seismicity. Unpublished M.A.Sc. Thesis, University of British Columbia, Vancouver
Rogers GC (1998) Earthquakes and earthquake hazards in the Vancouver area. In: Clague JJ, Luternauer JL, Mosher DC (eds) Geology and Natural Hazards of the Fraser River Delta, British Columbia. Geological Survey of Canada, Bulletin 525, pp 17–25
Ryder JM, Bovis MJ, Church M (1990) Rock avalanches at Texas Creek, British Columbia. Canadian J Earth Sciences 27:1316–132
Savigny W, Clague JJ (1992) Fraser Valley and Fraser Canyon areas. GeoHazards ‘92 Technical Tours Guidebook. Geotechnique and Natural Hazards Symposium, Vancouver, pp 47–99
Smith RH (1971) A study of a prehistoric landslide surface at Cheam Lake, east of Chilliwack, British Columbia. Unpublished B.A.Sc. Thesis, University of British Columbia, Department of Geological Sciences, Vancouver
Stuiver M, Reimer PJ, Bard E, Beck JW, Burr GS, Hughen KA, Kromer B, McCormac G, van der Plicht J, Spurk M (1998) INTCAL98 radiocarbon age calibrations, 24,000–0 cal bp. Radiocarbon 40:1041–1083
Thompson SC, Clague JJ, Evans SG (1997) Holocene activity of the Mt. Currie scarp, Coast Mountains, British Columbia, and implications for its origin. Environ Eng Geosci 3(3):329–348
Weichert DH, Horner RB, Evans SG (1994) Seismic signatures of landslides; the 1990 Brenda Mine collapse and the 1965 Hope rockslides. Bulletin of the Seismological Society of America 84:1523–1532
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Orwin, J.F., Clague, J.J. & Gerath, R.F. The Cheam rock avalanche, Fraser Valley, British Columbia, Canada. Landslides 1, 289–298 (2004). https://doi.org/10.1007/s10346-004-0036-y