Some 17 million people felt the 5.1-magnitude earthquake that shook Southern California Friday, U.S. Geological Survey said. USGS seismologist David Wald said the organization received 16,000 reports from people who felt the earthquake on the Did You Feel It? website. "About one in 1,000 are actually reporting... That's a pretty good [data] sample. If you're polling for political responses, that would be a huge sample," he said. The epicenter of the earthquake was relatively shallow, at a depth of 4.6 miles. It was centered about 1 mile south of La Habra, Calif., and 2 miles west of Brea, Calif.