More than 400 small earthquakes shake southern California

The Jurupa Valley in southern California has recently been shaken by a "swarm" of small earthquakes.

Since May 25, 432 earthquakes have affected an area covering only a few square kilometers, reported Monday the US Geological Survey (USGS).

The earthquakes, as a whole, have a magnitude of 0.8 to 3.2 and only a few have been significant enough to be felt, said USGS seismologist Robert Graves.

Do not panic, according to seismologists and geophysicists.

Andrew Newman, a geophysicist at the Georgia Institute of Technology, said that even though this earthquake swarm is receiving attention, such events usually do not precede a larger, more powerful, or more widespread earthquake.

As there is no major fault nearby, Graves said he believed the swarm was probably due to small cracks or a weak point in the Earth's crust.

"This area is a place of weakness and that is what causes these small earthquakes," he said.

"Great earthquakes occur on large faults," he said.

For example, Graves said that a magnitude 7 earthquake would have a fault length of about 30 miles and that an earthquake of magnitude 8 would have a fault length of 250 to 300 miles. The area affected by the swarm is only a few square kilometers.

There have been a few other swarms in the Jurupa Valley area. One was held in February and March of this year and the other in July and August 2018. Graves said swarms in these areas date back to the 1980s.

"In all these previous episodes, the largest earthquake was of magnitude 4," he said.

CNN's Cheri Mossburg contributed to this report.