Over the last few days, the Coachella Valley has experienced more than 20 earthquakes, causing concern among some residents.

An earthquake swarm is a series of small quakes that “may occur in a region for months without a major earthquake,” according to Britannica.. Getty Images/iStockphoto A swarm of a half-dozen ...

But in Southern California’s Imperial Valley, the earth has been shaking. In less than a day, more than 40 earthquakes shook the area around Holtville, the largest of which had a magnitude of 4.4.