17 April 2023
The Arroyo Seco landslide in Monterey County, California
Over the last week, concerns have been raised about a landslide that has developed in Arroyo Seco in Monterey County in California, USA. The best image I have found of the setting of the landslide was tweeted by Karl Cooke, a journalist with KION 5/46:-
There is a more detailed image of the landslide itself in a drone video of the landslide that was posted to Facebook by Felix Cortez, who is a reporter for KSBW Action News 8:-
The local authorities have rightly closed the road at the foot of the slope. The landslide is being monitored by the USGS.
The trigger for the landslide is not clear, but California has suffered a series of major rainstorms through the winter and the spring. In January, the high level of the river necessitated a helicopter rescue for a couple living in the area.
This landslide might well be a substantial headache for the inhabitants of the area and the people trying to keep them safe. Movement of the slope is likely to be hard to predict. One scenario is that the slope fully fails, creating a debris pile that can be removed, albeit at substantial cost. A more difficult scenario is that the slope does not fully fail, leaving a hazard on the slope that will place the road at risk. Experience from elsewhere suggests that decision-making in this situation is a challenge.
A tweet from KION News Channel 46 provides a really nice 3D view of the slope. It appears that the failure is occurring on geological strata that dip in parallel to the slope?
— KION News Channel 46 (@KION546) April 13, 2023