Earthquake in California

California was rocked by a 6.1-magnitude earthquake in the early hours of Sunday morning, the US Geological Survey (USGS) said.

Four mobile homes in the city of Napa were destroyed and two more had burned, according to a city government official. Reuters quoted that official as saying dozens were injured, two of them seriously.

The quake, which was the region's strongest since 1989, struck at 3:20 am local time, 6 kilometers (3 miles) northwest of American Canyon and 64 km northeast of San Francisco.

The USGS said the epicenter was located only 11 km under the earth's surface.

Residents in the area were quick to tweet their experiences, some thanking the "California alarm clock" for getting them out of bed. One tweeter, @andy_bms, posted a photo of the wine aisle at a local store in famed "Wine Country" following the tremors:

Power cuts

According to the Pacific Gas and Electric Company in Napa and Sonoma, 50,000 households were left without power, where a number of fires and minor structural damage has been reported.

Although though no serious damage has been reported, it is feared that the next "Big One," expected to be magnitude 7.0 or above, could occur within the next 30 years.

The California Highway Patrol (CHP) in the San Francisco Bay Area tweeted that early checking for obvious signs of structural damage were positive, and asked residents to report any signs of problems.

The CHP have since closed several off-ramps to highways and at least two roads in Napa Valley because of "significant roadway damage."

Drivers there were cautioned to be careful at an intersection of two state roads due to "cracks in roads."

California lies on the San Andreas Fault, which forms the tectonic boundary between the Pacific Plate and the North American Plate, two of the large moving plates that form the Earth's crust.

In 1906, a devastating San Francisco earthquake and subsequent fires destoyed over 80 percent of the city, killing more than 3,000 people.

In 1989, San Francisco was hit by 6.9-magnitude earthquake, also known as the Loma Prieta earthquake, resulting in 63 deaths and close to 4,000 injuries.

ksb/glb (dpa, AFP, Reuters)