A massive earthquake measuring 7.1 on the Richter Scale jolted Southern California, the USGS reported on Saturday. No casualties have been reported yet. According to the European-Mediterranean Seismological Centre, the epicentre of the earthquake was at depth of 40 km.The Saturday tremor comes a day after July 4 earthquake, which was the strongest earthquake in 20 years. It shook a large swath of Southern California and parts of Nevada on the July 4th holiday, rattling nerves and causing injuries and damage in a town near the epicenter, followed by a swarm of ongoing aftershocks. The 6.4 magnitude quake struck at 10:33 a.m. Thursday in the Mojave Desert, about 150 miles (240 kilometers) northeast of Los Angeles, near the town of Ridgecrest, California. Multiple injuries and two house fires were reported in the town of 28,000. Emergency crews dealt with small vegetation fires, gas leaks and reports of cracked roads, said Kern County Fire Chief David Witt. The Saturday earthquake was also epicentred around Ridgecrest. So far, the USGS has recorded 13 aftershocks.The National Weather Service of Las Vegas took to Twitter to inform about the quake. “Rolling #earthquake felt here at the NWS Hanford office at approximately 8:20 pm PDT. Lasted a good 45 seconds. Preliminary report of magnitude 7.1 quake with epicenter 11 miles from Ridgecrest, CA. #cawx,” The NWS Las Vegas said on micro-blogging site.