11 November 2016

St-Luc-de-Vincennes: a spectacular quick clay (?) slide in Quebec

Posted by dr-dave

St-Luc-de-Vincennes: a spectacular quick clay (?) slide in Quebec

A spectacular landslide occurred yesterday (Thursday) morning at the village of St-Luc-de-Vincennes in Quebec, Canada.  Reports suggest that an area about 200 m wide was affected, and as a result several houses have had to be evacuated.

The best image of this landslide that I have seen is on Twitter, courtesy of Elizabeth Laplante, a journalist at YVA Nouvelles:-

St-Luc-de-Vincennes

The landslide at St-Luc-de-Vincennes in Quebec, Canada courtesy of Elizabeth Laplante on Twitter

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That is an impressive slide.  Xania News has this less good in terms of resolution but incredibly interesting image too:

St-Luc-de-Vincennes

The landslide at St-Luc-de-Vincennes in Quebec, Canada via Xania News

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And this is the debris trail, via Mireille Roberge on Twitter:

St-Luc-de-Vincennes

The debris trail of the landslide at St-Luc-de-Vincennes via Mireille Roberge on Twitter

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The shape of the landslide, with the narrow outlet and large bowl, plus the high mobility of the very wet, muddy debris, suggests to me that this might be a classic quick clay landslide.  It would be interesting to know whether works had been undertaken on the slope to cause destabilisation.  This is a Google Earth image of the site from 2013:

St-Luc-de-Vincennes

Google Earth image from 2013 showing the site of the quick clay landslide at St-Luc-de-Vincennes

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There is no sign of instability in the field, but note right at the toe of the failure, where the debris has entered the stream, there is an active landslide in the imagery:

St-Luc-de-Vincennes

Google Earth image of the toe of St-Luc-de-Vincennes landslide in Quebec

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It is possible that this landslide retrogressed, and then triggered the runaway quick clay (?) landslide.

Previous posts about quick clay landslides