US Geological Survey data shows the first quake struck around 12:08 p.m. local time Saturday in Heber near the US-Mexico border, about 60 miles south of the Salton Sea, measuring 4.1 magnitude. There were dozens of tremors reported after the initial shock. 

Then on Sunday morning, a 4.5 magnitude quake struck 4 miles west-southwest of Niland and just east of the Salton Sea, USGS data showed. Dozens of tremors were reported as well. 

According to a USGS intensity map, the quakes were felt in Palm Desert, Indio, El Centro, and Mexicali. 

Last month, a series of earthquakes shook Pacifica in Northern California. Earlier this year, Los Angeles experienced a quake, and Humboldt County was hit in December. 

As for the state's southern region, it remains to be seen whether these swarms signal the potential for larger quakes.