Divers deployed by Dr. Siebert identified strange chimney-shaped vents on the lake ... areas at risk of collapse in the near future. Sinkholes, which are subsidence craters up to 100 meters ...

towering chimney-like structures, dubbed “white smokers,” that could serve as early warning signals for sinkhole formation. These vents offer new insights into the region’s groundwater ...

LATEST: Feb. 4, 11:20 a.m. The San Francisco Fire Department said a previously reported sinkhole in the city’s Marina neighborhood on Tuesday morning is actually a series of potholes.