Parts of Northern and Southern California have felt light shaking from earthquakes early this week. Here's how strong they were and which cities were closest to the epicenters.

Earthquakes’ sudden, rapid shaking can cause fires, tsunamis, landslides or avalanches. They can happen anywhere, but they’re most common in Alaska, California, Hawaii, Oregon, Puerto Rico and Washington, according to the Department of Homeland Security.

A 3.4-magnitude earthquake struck Southern California, then a 3.2 quake followed, the U.S. Geological Survey reported. /iStockphoto Back-to-back earthquakes shook the Northern California area after an early-morning tremor Thursday,