In some areas, like this road north of Anchorage, the earthquake caused the ground to liquefy and flow out from underneath roadways, collapsing the pavement into jagged chunks. That process, called liquefaction, happens when a quake shakes earth saturated with groundwater and made of a less rigid material than solid rock, like sand or mud. “It’s very important for us to recognize what areas are prone to liquefaction so that we can either avoid building there, or engineer around it,” said Jackie Caplan-Auerbach, a geology professor at Western Washington University.