It was just after 2:30 in the morning when the ground began shaking in Humboldt County, and it shook a lot on December 20th.
The ShakeAlert system that lets people know an earthquake has begun notified people miles away from the quake's epicenter near Ferndale. The people notified included Lori Dengler, geophysicist and longtime professor from Cal Poly-Humboldt, who happened to be in Sacramento when the quake hit.
The data are still being collected, but what's known already indicates some serious force, one of the stronger earthquakes in recorded California history. Lori Dengler tells us this and more in a visit two weeks after the main quake.