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Disaster Central: SCV prone to natural disasters

Posted: September 1, 2013 6:43 p.m.
Updated: September 1, 2013 6:43 p.m.

A photo shows the interchange between Interstate 5 and California State Route 14 following the 1994 Northridge earthquake.

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Editor’s note: September is National Preparedness Month, and The Signal begins a four-part series today examining natural disasters in the Santa Clarita Valley and ways to ready for them.

Part 2 of this series in Monday’s Signal will examine earthquake early warning and forecasting.

The strongest earthquake in recorded California history occurred just up the hill from the Santa Clarita Valley in an area commonly called the Grapevine.

Measuring 7.9 on the Richter scale, the Fort Tejon Earthquake struck around 8:20 a.m. on Jan. 9, 1857, on the San Andreas Fault, which divides California on two separate tectonic plates heading in different directions.

The quake tore the plates along nearly 200 miles of the fault line from Parkfield in Central California to Wrightwood east of Palmdale. At Fort Tejon, trees were uprooted and buildings destroyed. One person died when an adobe house in Gorman collapsed.

Since then — and no doubt long before — the Santa Clarita Valley has been shaken by earthquakes, scoured during savage storms or charred in wildfires. During its nearly 26 years of existence, the city of Santa Clarita has been declared a federal disaster area 11 times, said Donna Nuzzi, Santa Clarita’s czar of emergency management.

That doesn’t count state disaster declarations.

Greatest threat

“Our greatest threat is probably fire,” Nuzzi said in an interview.

In 2007, five fires erupted within days of each other in the Santa Clarita Valley, charring nearly 100,000 acres and destroying 21 homes.

In 2009, the Station Fire — said to be the worst in Los Angeles County history — swept around the valley to the east and moved into Acton, destroying homes there.

This year the Powerhouse Fire that started in late May burned up San Francisquito Canyon and destroyed 30 homes in Lake Hughes and surrounding areas, charring more than 30,000 acres.

Urban interface is the main reason the Santa Clarita Valley is so susceptible to wildfires, said Dean G. McGuire, Los Angeles County assistant fire chief.

“In a lot of areas we have brush that comes right up to people’s homes,” McGuire said.

Other conditions also contribute to major wildfires, he said. When that brush is tender-dry — as it is this year — and Santa Ana winds are blowing, the combination can spell disaster if a flame is sparked.

“In the Powerhouse Fire, we had 95-year-old growth that hadn’t burned,” he said. “And the wind was changing constantly.”

One of the best ways to prevent fires is “being alert and paying attention to what’s going on,” McGuire said.

For example, every year sees a number of fires starting alongside freeways due to vehicles towing trailers with chains dragging on the roadway, he said.

Other common causes of fires due to carelessness include cigarette butts flicked out of car windows and barbecues left unattended.

Whatever the cause of a fire, Los Angeles County fire officials agree the goal is to jump on it early.

“Los Angeles County has the most robust brush (fire) response in the Unted States,” McGuire said. “We have 23 to 27 different resources each day. ... We put a lot on into each fire to keep it small.”

The most effective strategies for local homeowers to prepare for disastrous fires is to clear brush around their homes ahead of time — and be ready to evacuate as soon as the order is given.

“If we feel strongly enough to tell you to evacuate, just move,” McGuire said. “We’ve had fires where firefighters burned up because people waited too long to get out.”

Most damage

Of the fire, storm and earthquake trifecta facing Santa Clarita Valley residents, earthquakes pose the greatest threat for extensive damage and prolonged loss of services, Nuzzi said.

The problem, says College of the Canyons geology professor Vincent Devlahovich, is the proximity of the San Andreas Fault.

“After the Northridge earthquake, people were asking, ‘Was it the big one?’ It was not the big one,” Devlahovich said in an interview.

The big one will come with the movement of the San Andreas Fault, which is just 20 miles from the center of Santa Clarita, he said.

The earth’s crust is made up of about nine major tectonic plates and many more minor ones, each moving relative to the plates around it, said Devlahovich, chairman of the college’s Earth, Space and Environmental Sciences Department.

The San Andreas Fault is the boundary between the Pacific Plate and the North American Plate, he said. It runs through southern Palmdale, along the Lake Hughes-Elizabeth Lake valley and through the Fort Tejon area, where it let loose in 1857 at a magnitude of 7.9 on the Richter scale.

The San Francisco Earthquake of 1906, also on the San Andreas, had nearly the same
magnitude and killed some 3,000 people. The Loma Prieta quake of 1989 — also on the San Andreas — reached just 6.9 magnitude, killed 63 people and caused extensive damage in San Francisco and Oakland as well as in Alameda, San Mateo, Santa Clara, San Benito, Santa Cruz and Monterey counties.

“The Santa Clarita Valley is in very, very close proximity to this fault,” Devlahovich said. But in Southern California, the San Andreas hasn’t moved for a long time, he said. And the longer it waits to move, the more pressure is built up.

“In the south we have a big kink in it,” he said of the fault. “Intervals of ruptures are much greater, and the seismic energy released is much, much, much higher.”

“All the faults that we’re living on,” he said, including those that moved in the Northridge and Sylmar quakes, “are all sub-faults of the (San Andreas) system.”

Devlahovich puts the chance of “the big one” — a rupture on the southern stretch of the San Andreas — at 80 percent within the next 20 years.

“It’s a matter of when it ruptures,” not “if,” he said. “I can’t say when, but it’s way, way overdue.”

Being prepared

Storms pose the third major threat of disaster in the Santa Clarita Valley. During El Nino years, canyon residents often become trapped on one side of a formerly dry creek and risk their lives if they attempt to cross.

“We don’t have flooding like you see in the Midwest, but we have had areas affected by mud flows and debris flows,” Nuzzi said. When heavy storms follow major fires that denude hillsides, the situation is considerably worsened.

The goal of National Preparedness Month is to encourage people to plan for disasters on personal, family, neighborhood and community levels, Nuzzi said.

“I don’t think scaring people is the right idea, but letting people know there are consequences” for being unprepared is important, she said. “Being prepared to recover — that’s what makes you successful.”

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