1 March 2019
US101 at Brookings: an interesting, disruptive landslide
On Tuesday, significant movement occurred on a large landslide in Oregon, closing the important US101 highway near to the coastal town of Brookings. This landslide (location 42.219, -124.374), which seems to have been triggered by heavy rainfall, is captured very nicely in a drone image Tweeted by Tidewater Contractors:-
Tidewater Contractors have also tweeted this rather splendid image of the main part of the landslide:-
This appears to be a large, moderately deep earthflow. Note the very clear scarps at the crown of the landslide and the beautiful array of tension cracks in the area in which the landslide mass steepened. Note also the very clear lateral scarps on the lower slopes towards the highway. The disruption to the road is very significant; Tidewater Contractors have tweeted a drone video showing the road damage, whilst the image below shows the impacts in more detail:-
There is an interesting article on Willamette Week that examines these types of landslide in Oregon in the context of climate change, drawing upon recent studies and expert knowledge. They note that these areas are being affected by both increases in groundwater level and by increased erosion of the coastal bluffs due to increased wave energy. This is the Google Earth imagery of the US101 landslide, with the image dated 3rd July 2016:-
The landslide is clearly identifiable in the Google Earth imagery, and there is evidence that movement has disrupted the road. The image demonstrates that the toe of the landslide is being eroded by wave action, leaving the slope more susceptible to the effects of increased groundwater levels.
The road is set to be closed for at least a month.