July 9, 2010 (San Diego’s East County) – Since the Easter Sunday earthquake in Mexico, strong tremors and aftershocks have moved northwards and westwards. The 5.4 magnitude quake near Borrego on July 7 had its epicenter in San Diego’s East County, leaving residents wondering whether the temblor is a late aftershock from the Mexico earthquake—or a precursor of a larger quake yet to come. The quakes also raise questions over whether it's time to invest in earthquake insurance--or at least seismic retrofitting for your home or business.
The April 4 quake in Mexico, which measured 7.2, has triggered aftershocks and new quakes along southern portions of the San Jacinto and Elsinore faults
Wednesday’s quake struck on the San Jacinto fault, which runs close to the border between Imperial and San Diego Counties. "We are viewing that as a triggered earthquake rather than an aftershock," seismologist Kate Hutton at Cal-Polytechnic State University told East County Magazine. "The 7.2 earthquake relieved strain but also rearranged the strain in the surrounding area."
The July 7 quake, centered 13 miles north-northwest of Borrego Springs, exhibited sideways horizontal motion to the northwest. In the past 50 years, four other quakes measuring 5.0 or higher have occurred within 20 km of this location. The largest quake recorded on the San Jacinto Fault was a 6.5 in 1968 at Borrego Mountain. The San Jacinto Fault is known as the most active earthquake fault in Southern California. (Details at the Southern California Seismic Network: www.scsn.org)
The Southern California Earthquake Center has forecast a potential major quake on the San Jacinto between 6.5 and 7.5 in magnitude. "It's definitely capable of a major quake," Hutton said.
The Elsinore Fault lies even closer to urban areas in San Diego, located just east of El Cajon and snaking northward along East County’s mountain towns, then into Temecula in Riverside County. The Elsinore fault has not had a major earthquake in over 100 years. But the major quake in Mexico has put pressure on neighboring faults, and a major quake along the Elsinore fault is possible, according to seismologists interviewed recently by the L.A. Times. http://www.latimes.com/news/local/la-me-quake-faults-20100630,0,3105452.....
But Hutton said that a major earthquake on the Elisinore Fault, while possible, is not likely in her view.
Is it time to take out earthquake insurance or make upgrades to improve your home or office's earthquake safety?
Standard homeowner policies do not cover earthquake damage. Earthquake policies are costly, however, with high deductibles. Still, an earthquake policy may make sense given the increased seismic activity in our region, particularly if you live in an older residence or are located close to a major fault line. For information on earthquake insurance options in California, see http://www.earthquakeauthority.com/index.aspx?id=13&pid=2.
Another option is to invest in seismic upgrades to your home or business, such as bolting a raised-foundation home to its foundation or reinforcing masonry fireplaces.
View earthquake safety guides and tips for homeowners and commercial property owners: http://www.seismic.ca.gov/.