Water, Dams, Earthquakes and Mudslides

Heavy rains are a concern for safety.

by Eric Holdeman / February 18, 2017

Lake Oroville Dam in California has brought dams back into the news, a little bit. There are, of course, hundreds or thousands of dams in every state, especially if you count the impoundments that hold back water for small lakes and large ponds. News organizations have contacted their state and local agencies for updates on what is happening in their local areas.

It was that type of action that likely got this story written, Earthquake Fears: Tacoma Power Plans Prolonged Low Levels at Lake. I'm sure that news about lowered water levels when the run-off is expected to be good this year will not please the people who have their favorite camping place right by the lake, but now the lake has moved/shrunk.

Here in the Pacific Northwest we have had a succession of rain and some snow events over the last 60 days. The soils are saturated and there have been some mudslides, but no loss of life. I saw one home in the news that looked like it had been destroyed.  I know the city of Seattle's Office of Emergency Management is poised to respond if slides start occurring. 

It was back in 1996 that Seattle really took it in the nose on landslides. Perkins Lane is particularly poised to slide again. As noted in the article, even a little bit of an earthquake shaker could do deadly damage right now. There might not be just these "bluff slides" but more deep-seated slides that impact entire neighborhoods. Our 2001 Nisqually earthquake happened in February, but it was an extremely dry winter that preceded the earthquake. Otherwise there would have been thousands of landslides in the region.

As noted, one homeowner admitted that he purchased the home knowing full well what the landslide risks are for the area. Risk perception is once again the issue — won't happen, won't happen to me!