2007 Alum Rock earthquake
|Date||October 30, 2007|
|Origin time||8:04 PDT |
|Magnitude||5.6 Mw |
|Depth||6.2 miles (10 km) |
|Areas affected||Santa Clara Valley
|Total damage||Minor |
|Max. intensity||VI (Strong) |
The 2007 Alum Rock earthquake occurred on October 30 at 8:04 p.m. Pacific Daylight Time in Alum Rock Park in San Jose, California. It measured 5.6 on the moment magnitude scale and had a maximum Mercalli intensity of VI (Strong).
The Alum Rock earthquake was then the largest in the San Francisco Bay Area since the 1989 Loma Prieta earthquake, which measured 6.9 on the moment magnitude scale, but was later surpassed by the 2014 South Napa earthquake. Ground shaking from the Alum Rock quake reached San Francisco and Oakland and other points further north. Sixty thousand felt reports existed far beyond Santa Rosa, as far north as Eugene, Oregon.
The shock originated on the Calaveras Fault and ruptured an area of the fault for a length of about 5 km (3.1 mi) beginning at the hypocenter and extending southeast. No surface trace of the earthquake along the fault. David Oppenheimer, a seismologist at the United States Geological Survey (USGS), said that although the quake was felt as a strong jolt over a wide region, it was more significant because it caused stress changes in the Calaveras Fault and the nearby Hayward Fault.
Intensity VI (Strong) effects included broken windows and items that were knocked off store shelves, but the event caused no serious damage or injuries. Some parts of the Bay Area felt the rupture for up to 15 seconds.
ElarmS, an earthquake early warning system, accurately predicted the quake seconds before it struck, correctly estimating the earthquake's magnitude to within 0.5 magnitude units using only three to four seconds worth of data. Scientists with the California Integrated Seismic Network hope to refine the system to provide a 10-second warning in a similar quake to residents of Oakland and San Francisco.
- USGS (September 4, 2009), PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey
- USGS. "M5.6 - San Francisco Bay area, California". United States Geological Survey.
- "Magnitude 5.6 - SAN FRANCISCO BAY AREA, CALIFORNIA". USGS. 2008-09-23. Archived from the original on 7 October 2008. Retrieved 2008-10-10.
- Perlman, David (2007-10-31). "Quake raises danger of more action on volatile Hayward Fault". San Francisco Chronicle. Retrieved 2008-10-10.
- Early warning system predicted shaking from Oct. 30 quake, PhysOrg.com, December 11, 2007. Retrieved October 16, 2008.
- Oppenheimer, D. H.; Bakun, W. H.; Parsons, T.; Simpson, R. W.; Boatright, J.; Uhrhammer, R. A. (2010), "The 2007 M5.4 Alum Rock, California, earthquake: Implications for future earthquakes on the central and southern Calaveras Fault", Journal of Geophysical Research (American Geophysical Union) 115 (B8), doi:10.1029/2009JB006683