Last week
’s Paso Robles quake may serve as a reminder to South Valley
residents that disaster can strike close to home suddenly and
harshly, as it has done before.
Last week’s Paso Robles quake may serve as a reminder to South Valley residents that disaster can strike close to home suddenly and harshly, as it has done before.
Scientists and public officials encourage residents to use the 6.5-magnitude earthquake on Dec. 22, felt from Los Angeles to San Francisco, as a reminder that everyone must be prepared should a natural disaster strike.
“I think that the past is a fingerprint to the future, and we know that this is the boundary between the two giant tectonic plates: the North-American and Pacific plates,” said Charles P. Watson, geologist and president of Seismo-Watch, a corporation collecting earthquake news and information. “And since those plates are in constant motion, we would expect earthquakes in the future.”
There is a 62 percent probability of at least one magnitude 6.7 or greater quake, capable of causing widespread damage, striking the San Francisco Bay region before 2032, according to the U.S. Geological Survey.
To prepare for that eventuality, Morgan Hill will offer a series of disaster preparedness classes in early February, preparing residents to care for themselves and their neighbors when emergency services are overwhelmed, as is usually the case after a significant earthquake.
Monday’s earthquake, which killed two women when an unreinforced landmark clocktower collapsed in downtown Paso Robles, was the first to result in fatalities since the 6.7-magnitude Northridge earthquake of 1994.
The biggest earthquake in recent history struck northern California on Oct. 17, 1989, jarring Morgan Hill and causing widespread damage and power outages throughout the Bay Area. The major 7.1-magnitude quake killed 63 people and injured 3,757. The temblor caused little structural damage to Morgan Hill except to the 1886 Morgan Hill House.
Morgan Hill sits in the Calaveras fault zone, west of the well-known San Andreas fault, which contains a number of different strands of faults that could produce a sizable (stronger than 5.5-magnitude) earthquake. The most active of those is the Calaveras fault, which runs along the east side of the valley, from outside Hollister, past Gilroy and Morgan Hill, through the Coyote Reservoir and up through the Calaveras Reservoir at the base of Mt. Hamilton.
The Calaveras fault is the largest fault in Santa Clara County, and longer faults are usually responsible for larger earthquakes.
“There’s a lot of work that needs to be done on predicting certain magnitudes of certain faults,” Watson said.
Some of the other nearby faults are also capable of magnitude 5.0 to 6.0 earthquakes.
“I would expect to see lower- to mid-6’s from the Calaveras fault zone, really,” Watson said. “It’s capable of larger ones, but my research shows it’s probably not likely. That’s its history.”
According to the USGS, sizable quakes have made the South Valley quiver since the 18th century, several along the Calaveras.
“There were some dandy ones back around the turn of the century,” Watson said.
Besides the great 1906 earthquake, which measured 7.9, according to USGS, a magnitude 5.8 quake was centered in Morgan Hill on July 6, 1899. Two years earlier, a 6.3 earthquake centered in Gilroy shook the area.
Some other recent substantial temblors include one of magnitude 5.8 in 1979 and the Morgan Hill earthquake on April 24, 1984. That 6.2-magnitude quake was centered eight miles north/northwest of Morgan Hill on the Calaveras fault.
Twenty-seven people were injured, more than 500 homes and 43 commercial buildings were severely damaged, costing $8 million in damages, Watson said.
Watson encourages South Valley residents to use the Paso Robles earthquake as a motivation to prepare for the next local shaker.
“Use this as a wake-up call to check emergency supplies, talk to family members about an emergency plan, what to do in case something happens,” he said. “Take this time to get ready because you never know when an earthquake is going to happen.”
The City of Morgan Hill, working with the Police department, has established a Community Emergency Response Teams (CERT) program, which, for several years, has trained residents to respond properly to disasters. The City of Gilroy is currently organizing its first series of CERT classes. Details on the next series of hands-on classes are not set yet but will be given 7-10 p.m. on Tuesdays or Wednesdays beginning in February. There is a nominal fee to sign up.
Details: on CERT, e-mail mh****@****ic.com or call Donna Krein, 779-8068.
