The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
On 13 March 2023, an unusual and interesting landslide occurred in the Sherman Oaks suburb of Los Angeles in California, damaging or destroying at least three houses. The Los Angeles Fire Department has a good news page about this event, which occurred early in the morning. Fortunately, there were no casualties.
There is good aerial imagery of the aftermath of the landslide posted to Youtube by NBC News:-
This appears to show a deep-seated block failure with a near-vertical rear scarp:-
I believe that the location of the landslide is shown in the Google Earth image below:-
If correct, this means that the landslide is located at [34.1398, -118.4285].
California has been deluged by rainfall over the winter, so high groundwater levels might be at least a partial explanation for this landslide. However, it appears that the failure occurred in dry weather.
There is an interesting short view in the NBC video that I would investigate if I was asked to try to understand the cause of the landslide. It appears at about 42 seconds into the piece:-
This section appears to show an unsupported excavation on the slope – and note what I would interpret to be landslide debris in the image. It would be interesting to know more about that excavation, including the timing, the scale and the stability calculations that determined that it should be unsupported.
I cannot speculate on the cause of this landslide, but as this area of California is known to have a high level of landslide hazard, excavation into any slope needs to be undertaken with great caution.
