With small slide below Interlaken, soggy March brings landslide concerns

An unbelievably soggy March has neighbors in the sloping areas on the north of Capitol Hill worried about landslides.

A small slide closed 14th Ave E between Boyer and Lynn to through traffic Saturday morning. With continuing rains, you can expect to see more mud.

March has already reached its average rainfall totals following weeks of even wetter than usual weather around Seattle.

CHS has reported on small slides over the years and concerns about the slopes of northern Capitol Hill and around Interlaken Park. Our nature writer documented the landslide risk of the area in 2014 including the Hill’s geologic past of glacial till and water-pooling clay:

Then we come in. The grade is altered, creating new faults. Hills are denuded of trees, which hold slopes and mitigate flooding. Barriers to natural water flow diverts it toward unforeseen consequences. People understandably want views and build on cliffs, changing the loads on hills. Generally things more even more unstable. West Capitol Hill, Interlaken, North Capitol Hill. Slides every decade going back in our modern record. I won’t tally the slides in Hill history — that would take too long.

For the most part, recent slides have been mostly limited in damage. In 2011, cracks from the sliding hillside forced an indefinite closure of Interlaken Drive. It reopened after repairs five months later.

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2 thoughts on “With small slide below Interlaken, soggy March brings landslide concerns

  1. Was tempted to almost buy a house at the top of Interlaken. No one wants to disclose slide activity when they sell, or they use vague terms about ECA. Ultimately hired a geoengeering company who advised me entire garden might slide in 20yrs, and was marked as high risk by city. Provided report to seller, who refused to disclose to other buyers.

    The whole area is unstable, and any steep slope is ultimately impossible to secure. Buyer beware !

  2. Not a big surprise. Interlaken Blvd was closed to cars for what – half a year or more just below the Hebrew Academy a few years ago because of slide concerns. The city finally decided it was staying put and (to my great sadness as a bicycle commuter) reopened it, but I wouldn’t be surprised with all the recent rain that it might be on the move again – there was a pretty nice sized gap that opened in the blacktop the last time.

    It’s actually surprising that it doesn’t happen more often… the soil is so loose around here – they used water and hoses to sluice the bluffs down the hill to downtown 100 and bit years ago… I grew up in hill Pittsburgh, but it was a lot of rock.. take a shovel there and you’d hit something solid a few inches down (or at least it always seemed to feel that way…) There you only had to worry if your house was built over top of an old coal mine… Believe you me, when we were looking at houses here, not being located on or below a bluff was certainly a factor. We also looked at the bowl down there in the upper part of Madison Valley – my first thought was I’ll bet the basements here are wet every time it rains… though I never imagined that it could be as tragic as it turned out to be.