Three homes have been evacuated following a landslide close to the Salt Water State Park in Des Moines in King County, Washington State, on Friday 27 March 2015. The event started at about 8.30 am and proceeded slowly throughout the day, enabling the residents of the homes to remove valuables and evacuate safely, though at about 3.00 pm the rate of collapse increased sharply, resulting in the loss of most of the gardens of one of the properties, as well as minor damage to the building itself.
Aerial photograph of the 27 March 2015 Des Moines landslide. King5.
Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. However no exceptional rainfall has been reported in King County, or other areas of (often wet) Washington State in the past few weeks, making it unlikely this was the cause on this occasion.
Closer shot of the 27 March landslide, showing part of a structure that has collapsed downslope. KomoNews.
The situation is being monitored closely by local authorities, who have not ruled out the possibility of further evacuations if the landslip, currently about 60 m wide, continues to grow. Puget Sound Energy have cut off gas and electricity supplies to the evacuated properties as a precaution.
The approximate location of the 27 March 2015 Des Moines landslip. Google Maps.
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