A disaster as big as Aldercrest is rare, Burns said. But he is watching a couple of smaller developments in the Portland and Oregon City areas that he didn't want to identify for fear of alarming or angering homeowners. I have some pictures now, and hopefully I won't have to use them as a before photo. Ancient landslides can be built on, engineers say, and once moving, they can be stopped in many cases. But doing so is expensive and requires specialized technical fixes.
Commuters pass beneath one as they ride westside light rail into Portland.
These three slides have been stabilized in years past with drainage and buttressing. Some say two decades of relatively drier weather lulled Oregonians into overestimating the stability of hillsides. We just didn't know how much until these things started to move. It's caused some rethinking. At Aldercrest, homeowners didn't know they were putting down roots on a slope that geologists say has moved, off and on, for probably thousands of years.