When you look at photos of sinkholes, the deep pits don't even look real -- they look like perfectly round tunnels, plunging toward the center of the earth. How does the soil shift and give way to swallow people, houses, cars and whatever else is around?
It's a timely question, because just east of McMinnville, traffic is being re-routed after a sinkhole swallowed up part of Oregon Route 219. KOIN reports that a section of the road will be closed off in both directions while Oregon Department of Transportation engineers and maintenance staff evaluate the area for repairs.
And earlier this year, The Oregonian reported a Portland woman tumbled into a 20-foot-deep pit when she went outside to her backyard looking for her dog at night. Luckily a passerby heard her call for help and called 911.
The Independent reports that a sinkhole is created by erosion and the drainage of water. They can span just a few feet or across a city block. They can also be triggered by human activity -- the one in Portland might have formerly been a well, and many sinkholes making headlines today are due to human construction.
There are two basic types: a cover-subsidence sinkhole, which is created slowly over time, and a cover-collapse sinkhole, which appears suddenly.
KOIN reports that 50 (yes, 5-0) sinkholes have popped up in Portland, many in the north end of the city. Most were caused by aging waterpipes and old roads that don't have a lot of support.
This story originally appeared on Oregon Public Broadcasting.