[Magoo]

Whatever the particular trigger to the slide, which can be argued ad nauseam, just look at the pics. Anyone in their right mind could see the (exfoliation) fracture patterns and the general formation of the valley. This was just a matter of time.

[fyshy]

I agree. In reviewing the pictures, it is clear that the exfoliation is so extreme that the recent earthquakes allowed the fracture patterns to freeze and thaw simultaneously, then "whoops, there go gravity".