In early January, a giant sinkhole formed at an intersection in the West Oak Lane neighborhood of North Philadelphia after a water main break. Just two weeks earlier, the city reopened a section of the Schuylkill River Trail in Center City that had been shut down for two months due to a sinkhole. Last summer, some residents of Point Breeze in South Philly also waited two months for a sinkhole on their block to be repaired.
Laura Toran is a hydrogeologist and professor emeritus of environmental geology at Temple University. The Conversation U.S. asked her what causes sinkholes, whether Philly is particularly prone to them, and why repairs can take so long.
