September 10, 2009

Contact: Don Drysdale
             Carrie Reinsimar

SACRAMENTO – Most people understandably associate the Reno/Lake Tahoe area with scenic beauty, outdoor activities, and entertainment. But earthquakes? Not so much, although 15 years ago on September 12, the region received a jolt when a magnitude 6.2 quake struck the region.

“Fortunately, there were no injuries and little damage,” said Dr. John Parrish, State Geologist of California and head of the California Geological Survey (CGS). “The next time – and there will most certainly be a next time – the region may not be so lucky.
“The anniversary of this event is a reminder to area residents: Think about your personal preparation. Recent studies have indicated the Tahoe basin is more earthquake-prone than previously believed. Are you as ready as you need to be in a seismically active area?”

At minimum, Parrish advised, residents should have a “grab and go” emergency kit with adequate water, food, prescription medicine and other essentials.

“People have heard this time and again, but they sometimes put it off until there’s an emergency: Be prepared to get by without any outside help or resources for at least three days,” Parrish said. “If you do nothing else, be sure to discuss where you will meet your family in the event an earthquake occurs when you’re in different locations. Roads may be blocked and lines of communications may fail.”

More information about being ready for an earthquake can be found on the CGS Web site,
The September 12, 1994 event – known as the Double Spring Flat earthquake – was centered 12 miles from Gardnerville, Nev., and felt as far away as Sacramento, San Francisco, Fresno and Elko, Nev. Within the following several days, there were half a dozen aftershocks of magnitude 4 or greater.

Earthquakes of magnitude 3 or greater can cause minor localized damage while those in the magnitude 5.5 range can do structural damage to buildings made of unreinforced masonry. The Double Spring Flat quake woke many up people (it occurred at 5:23 a.m.) and knocked items off shelves, but it did not do any serious damage.

“Earthquakes with the potential to cause multiple fatalities in some countries often do relatively minimal damage in California because of our robust building codes and practices and stringent enforcement,” Parrish said. “Still, there are many buildings around the state that are not built or retrofitted to the most current seismic standards, so there’s still a widespread risk factor.

“Moreover, building codes and retrofitting projects are geared to protect the public at large, not individuals or families. The California Geological Survey urges people to take responsibility for their own welfare at that level. Today is a good day to start getting prepared.”

There are several faults thought capable of generating large earthquakes in the region that encompasses Lake Tahoe, Truckee and Carson City, Nev., including the Genoa, Antelope Valley, Incline Village and West Tahoe faults. The latter fault runs under part of Lake Tahoe and may be able to generate damaging seiche waves (essentially a tsunami in an enclosed body of water).

Recently, the Scripps Institute of Oceanography issued two studies suggesting the earthquake risk in the Lake Tahoe basin is greater than previously thought. One study concluded that the West Tahoe Fault historically has generated a magnitude 7 earthquake every 2,000-3,000 years and is well overdue.

Largest Reno/Lake Tahoe-Area Earthquakes

                                Date                            Magnitude                   Location
                         March 15, 1860                        6.5              Between Carson City and Pyramid Lake
                         June 3, 1887                            6.5              Carson City, Nev.
                         Dec. 27, 1869                          6.4              Near Virginia City, Nev.
                         Sept. 3, 1857                           6.3              Western Nevada/Eastern Sierra Nevada
                         Dec. 27, 1869                          6.2              Near Carson City, Nev.
                         Jan. 24, 1875                           6.2              Honey Lake
                         April 29, 1888                          6.2              Mohawk Valley
                         Sept. 12, 1994                         6.2              SE of Lake Tahoe, on Nevada state border
                         June 25, 1933                          6.1              Yerington, Nev.
                         Aug. 1, 1975                            6.1              Oroville
                         Sept. 12, 1966                         6.0              About 6 miles northeast of Truckee
                         Dec. 29, 1948                          6.0              About 6 miles north of Truckee