Sendai rock avalanches talk

Coseismic rock avalanches in the Himalaya: a palaeoseismic data source : 

Coseismic rock avalanches in the Himalaya: a palaeoseismic data source Wishart Mitchell, David Petley and Stuart A Dunning Google: “landslide blog”

Palaeoseismic catalogues : 

Palaeoseismic catalogues There is an urgent need to create long term palaeoseismic catalogues to allow earthquake hazard assessment But very difficult to achieve Need multiple data sources

Historical record of large earthquakes : 

Historical record of large earthquakes Roger Bilham http://cires.colorado.edu/~bilham/

Slide 4: 

Roger Bilham http://cires.colorado.edu/~bilham/

Rock avalanches may be a useful data source : 

Rock avalanches may be a useful data source

Pros and cons of rock avalanches : 

Pros and cons of rock avalanches Pros: Strong relationship with very large earthquakes(?) Leave a large, long term trace in the landscape Cons: Unproven Could be triggered by climate, deglaciation or maybe time? Time-consuming From Malamud et al., 2004. Earth and Planetary Science Letters

Slide 7: 

Himachal Pradesh, N. India

Slide 9: 

Cambrian , Ordovician and Silurian metasediments

Kay parameters : 

Volume: 900 million m3 Fall height: 1,300 m Runout distance: 6,000 m Farboschung angle: 12.24º Max. run-up height: 350 m Maximum velocity: >80 m/sec Deposit area: 12 km2 Kay parameters

Age of Keylong Serai rock avalanche : 

Age of Keylong Serai rock avalanche 10Be Cosmogenic dates processed by GNS Science, New Zealand Samples from quartz veins on the upper surfaces of mega-clasts in the landslide deposit COS 1 (GNS Be 1781): 7670 ± 310 calendar years COS 2 (GNS Be 1782): 7250 ± 310 calendar years COS 3 (GNS Be 1783): 7630 ± 350 calendar years ERROR WEIGHTED MEAN = 7510 ± 110 calendar years

A co-seismic event? : 

A co-seismic event? Climate driven? Present climate is high arid desert Palaeoenvironmental records indicate a wetter monsoon driven early Holocene But the period 8.0-7.2 ka cal years was comparatively dry, and getting drier Deglaciation? OSL dates indicate ice retreat in this area earlier 10.2 ± 2.1 ka cal years Co-seismic? Very deep-seated morphology might support this (McSaveney and Davies 2004)

Earthquake moment magnitude vs volume of maximum landslide (VLmax) : 

Earthquake moment magnitude vs volume of maximum landslide (VLmax) Keylong Serai From Malamud et al., 2004. Earth and Planetary Science Letters

Conclusions : 

Conclusions Kelong Serai suggests that very landslides may be a useful tool for creating a landslide catalogue Now needs systematic campaigns to identify and date very large landslides Needs to be backed up by palaeoclimate and palaeoglacial analyses Can we isolate a morphological indicator of a seismic trigger?