Details are still trickling in - from the American Geophysical Union's Landslide Blog:
Jiuzhaigou County: a shallow magnitude 7.0 earthquake in Sichuan Province on 8th August 2017
At 13:49 UT (21:49 local time) on 8th August 2017 an earthquake struck Jiuzhaigou County in Sichuan Province in China. At the time of writing the magnitude of this event is unclear – the Chinese media are reporting M=7.0, whilst the USGS currently has M=6.5 – but either way this is a significant event. In both cases the depth is considered to be very shallow – c. 10-20 km – which means that there is a high potential for landslides. Currently, the level of loss is not clear, and is unlikely to be so until the sun comes up in a few hours, but estimates range from 40 to 190 fatalities, with a median value of 102, according to James Daniell of EDIM – CAT news.
Of course this area is no stranger to significant earthquakes. The earthquake in Jiuzhaigou County has occurred to the west of the ruptures that generated the 2008 Wenchuan earthquake. It is a characteristic of earthquakes in this area that they generate large numbers of landslides. The landscape in this region of China is steep and high, and the slopes have been preconditioned for failure by frequent earthquakes and intense rainfall events. Early indications are that this was predominantly a strike-slip earthquake – experience suggests that these events tend to generate intense landsliding close to he fault rupture, with rapid attenuation of landslide density away from the fault. It will be interesting to see if this event matches this pattern.
Strike-slip is what we have to look forward to with the Cascadian Subduction Zone - nasty stuff.
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