An earthquake measuring 4.5 on the Richter scale shook the downtown Los Angeles, parts of the High Desert, San Pedro and coastal and inland Orange County, but was not felt as far south as San Diego, although no injuries or damage were reported.The epicenter of the quake, which happened on Friday, January 09, 2009 at 03:49:46 UTC Coordinated Universal Time ) and Thursday, January 08, 2009 at 07:49:46 PM at epicenter local time reported by the U.S. Geological Survey, was 3 km (2 miles) SSW (202°) from San Bernardino, CA, 5 km (3 miles) NNE (19°) from Colton, CA, 7 km (4 miles) E (94°) from Rialto, CA, 87 km (54 miles) E (86°) from Los Angeles Civic Center, CA, with the depth of 14.1 km (8.8 miles).

The USGS originally believed the quake measured 5.0 then officials later downgraded it to 4.5.

Experts say this loose soil could liquefy in the event of a massive quake, causing buildings to topple. As of 2005, about 100 unreinforced masonry buildings in the city lacked any form of retrofitting, according to city and state records.