17 December 2015
Mount James Turner rock avalanche
Drew Brayshaw has tweeted this image of a rock avalanche that apparently occurred on Mount James Turner yesterday:
Mount James Turner is close to Whistler in British Columbia, western Canada. This looks to be a large, very mobile rock avalanche event, with a steep upper portion and a long track. Note the small flow that appears to have left the main flow mid-track, and then rejoined the main flow after descending a step. There is some evidence of dust on the margin of the landslide. Drew also tweeted a pre-failure image of this part of Mount James Turner:
The landslide appears to have originated from an unsually steep rock cliff on the edge of Fingerpost Ridge and will have had a substantial freefall element. Based on the image, and correlating with Google Earth, the runout distance that is visible will be about 2 km. However, there may be a longer non-visible component. The top of Fingerpost Ridge is at about 2600 m, whilst the foot of the steep slope is at about 2300 m according to Google Earth. The toe of the visible part of the landslide is at 1900 m.
Interestingly, at the toe of the landslide there appears to have been a lake – named Berna Lake:
Is this the snowy apparently-deformed mass that appears to lie at the toe of the landslide in the first image? Canada has a good seismic network, so it will be interesting to see if this landslide has been captured on those sensors.