Wednesday, October 31, 2007
According to the United States Geological Survey (USGS) a magnitude 5.6 earthquake, lasting about 30 seconds, struck at 20:04:54 (PDT) on October 30, 2007, with the epicenter being five miles north, northeast of Alum Rock California and nine miles northeast of the center of San Jose. The actual coordinates given by USGS put it along the border of San Jose and Milpitas in the hills near neighborhoods in both cities. The quake was felt as far away as the California communities of Sacramento, Sonoma, and Los Banos. It was the most powerful quake in the San Francisco Bay Area and Silicon Valley since 1989.
At least ten aftershocks had been reported by 8:35 p.m with magnitudes ranging from 1.3 to 1.8.
Phone service, including cellular phone service, was reported to be down in some areas around the epicenter. Residents and business owners also reported their homes shaking.
According to the USGS, damage could be "moderate to heavy" and Rafael Abreu of the USGS said that the earthquake is considered "moderate," but so far there are "no injuries." The quake was reported at a depth of 9.2 km (5.7 miles).
USGS predicts a 30% chance of strong (magnitude >5) aftershocks in the next seven days, with a 5-10% probability of aftershocks stronger than the main quake. Additionally, USGS predicts approximately 15-40 small (magnitude 3-5) aftershocks.
The USGS reports that the quake was centered on the Calaveras Fault, and was the most powerful earthquake on that fault since the 1984 Morgan Hill earthquake.
== Sources ==
"5.6 Earthquake Hits Calaveras Fault" — NBC11.com, October 30, 2007
"Magnitude 5.6 - San Francisco Bay Area, California" — USGS, October 30, 2007
"USGS preliminary earthquake report" — USGS, October 30, 2007
"USGS map of intensity based on survey responses" — USGS, October 30, 2007
"Seismograph from Stanford Telescope for 10/30/2007" — USGS, October 30, 2007
"Aftershock Forecast" — USGS, October 30, 2007
"5.6 earthquake hits near Alum Rock" — Mercury News, October 30, 2007
Ron Harris, Associated Press. "Moderate earthquake shakes San Francisco" — Yahoo News, October 30, 2007
RadioMatthew.com. "Alum Rock Earthquake" — MaxWiki, October 30, 2007