Intense earthquake swarm near Salton Sea, Southern California

An intense earthquake swarm is taking place near the Salton Sea in Southern California, U.S. on June 5, 2021, starting with M2.2 at 08:05 UTC (01:05 LT).

The USGS has registered 285 earthquakes by 21:24 UTC. The swarm is still in progress and new earthquakes are being registered every few minutes, sometimes 2 or 3 within 1 minute.  (Update: 805 earthquakes were registered by 21:29 UTC on June 6)

The strongest so far was M5.3 at 17:55 UTC (10:55 LT). The quake struck 11 km (7 miles) W of Calipatria and 11 km N of Westmorland at a depth of 5.8 km (4.6 miles).

3 000 people are estimated to have felt strong shaking, 9 000 moderate, and 201 000 light.

More than 1 050 people submitted 'I felt it' reports.

Image credit: TW/SAM, Google

M2.5+ earthquakes on June 5, 2021. Image credit: TW/SAM, Google

The USGS earthquake scientists said earthquake swarms in this area are not really unusual.

"We last had a swarm right near today’s activity in 2005. And the entire region surrounding the Salton Sea is known for having swarms; we had two just last fall."

According to the USGS forecast, over the next 7 days there is an 8% chance of one or more aftershocks that are larger than magnitude 5.3. It is likely that there will be smaller earthquakes, with 2 to 46 magnitude 3 or higher aftershocks. Magnitude 3 and above are large enough to be felt near the epicenter. The number of aftershocks will drop off over time, but a large aftershock can increase the numbers again, temporarily.

• The chance of an earthquake of magnitude 3 or higher is > 99 %, and it is most likely that as few as 2 or as many as 46 such earthquakes may occur in the case that the sequence is re-invigorated by a larger aftershock.
• The chance of an earthquake of magnitude 5 or higher is 13 %, and it is most likely that as few as 0 or as many as 2 such earthquakes may occur.
• The chance of an earthquake of magnitude 6 or higher is 1 %, such an earthquake is possible but with a low probability.
• The chance of an earthquake of magnitude 7 or higher is 1 in 700, such an earthquake is possible but with a low probability.

Featured image credit: TW/SAM, Google