6.4 Magnitude Earthquake Strikes Southern California

LOS ANGELES, CA — A 6.4 magnitude earthquake struck near Ridgecrest, California at 10:33 a.m. Thursday, and shaking could be felt all the way into Mexico and along the Southern California coast. The quake, estimated to have been felt by about 15 million people, ended a more than two-decade long quiet period in the state's seismic history.

Though the quake struck in a sparsely populated Kern County community bordering San Bernardino County, it triggered about two dozen incidents ranging from medical emergencies to structure fires around the city of Ridgecrest, according to the Kern County Fire Department.

Authorities reported that several buildings had been found with minor cracks, along with broken water mains, downed power lines and rockslides on certain roads. Emergency operators throughout Southern California were flooded with calls.

The quake, epicentered 10 miles northeast of Ridgecrest, (about 125 miles north of Los Angeles), was quickly followed by another 4.0 magnitude temblor. Shaking could be felt for hundreds of miles. In the Los Angeles region, the rolling could be felt for about 20 seconds.

Aftershocks continue to rattle the region, including six quakes of 4.0 or larger magnitude within 90 minutes of the major quake. Two minutes after the largest quake, a 4.7 magnitude earthquake struck the region followed by a 4.0 quake another two minutes later.

The U.S. Geological Survey warned residents to expect more shaking throughout the week.

"According to our forecast, over the next 1 Week there is a 9% chance of one or more aftershocks that are larger than magnitude 6.4. It is likely that there will be smaller earthquakes over the next 1 Week, with 50 to 700 magnitude 3 or higher aftershocks," the USGS tweeted.

A state of emergency was later declared in Ridgecrest and signed by Gov. Gavin Newsom, and 15 emergency-room patients were transferred to Palmdale Regional Medical Center while Ridgecrest Regional Hospital was being evaluated for structural damage.

Ridgecrest is a small town off Highway 395 that connects the Los Angeles region to Death Valley Park and Sequoia National Park. Within minutes, more than 20,000 people reported having felt the shaking, according to the U.S. Geological Survey.

San Bernardino County Fire Department tweeted that "no injuries reported, however buildings and roads have sustained varying degrees of damage."

Residents close to the epicenter reported feeling a rolling quake as opposed to a jarring temblor. The rattling knocked over shelves in homes closest to the epicenter.

Inundated with calls, both the Los Angeles Police Department and Los Angeles Fire department issued statements, asking residents not to call 9-1-1 about the quake. They received no reports of damage or injuries in the LA area.

The Los Angeles Fire Department reported that "all 106 fire stations are out conducting a strategic survey of their districts to determine if any damage exists. Once this process is complete, an overall assessment of the impact in the City of Los Angeles will be compiled."

Similarly, emergency responders in San Bernardino and Kern counties are surveying surrounding communities for damage.

The last time Southern California endured a quake this large was the 1994 Northridge quake that killed dozens, collapsed roadways and caused billions in damage. However, Thursday's quakes have struck a far less populous region.

Seismologist Lucy Jones offered reassuring words for the rattled region.

"M6.4 on a strikeslip fault about 10 miles from Ridgecrest. Not the San Andreas fault," she tweeted. "It is an area with a lot of little faults but no long fault."

According to Jones, the region's preeminent seismologist, a for 4.2 magnitude quake that rattled the region about a half hour before the big one hit was a foreshock.

We've seen shaking along this same fault line before with the most intense earthquake activity last striking in the 1980s, she added.

The tremblor was the largest in Southern California since 1999, when the 7.1 magnitude Hector Mine quake struck the Mojave Desert.

City News Service contributed to this report.