ADVANCES SPEED QUAKE RESPONSE SCIENTISTS LEARN FROM 1994 EFFORTS.

Byline: Troy Anderson Staff Writer

In the eight years since America's costliest urban natural disaster hit the San Fernando Valley, scientists have made major strides in understanding earthquakes though they still are a long way from predicting the next big temblor.

The 6.7-magnitude Northridge Earthquake that hit at 4:31 a.m. Jan. 17, 1994, raised many questions about how quakes occur and led seismologists to develop computerized systems that can identify the epicenter within minutes and create maps of the areas where the shaking is most intense.

Information that took hours or days in 1994 can now be sent over the Internet and satellite transmission systems to emergency agencies, speeding rescuers directly to the hardest-hit spots.

``We have been looking at what we can do to help people and have recognized that recording and turning around the information about what happens in an earthquake extremely rapidly is a real public safety benefit,'' said Lucy Jones, scientist-in-charge for Southern California at the U.S. Geological Survey, which is housed at the California Institute of Technology in Pasadena.

The Northridge Earthquake - actually centered in Reseda - killed 57 people, injured more than 9,000 and caused more than $40 billion in damage. Insurance carriers have paid out more than $15 billion on 630,000 claims.

Since the disaster, the biggest advance in technology has been the TriNet system, a real-time network of 200 digital sensors in Southern California and 400 more statewide that provide earthquake data to computers at Caltech. Those computers send the information via the Internet to state and local emergency response agencies, electric and gas utilities, telephone companies and television and radio stations.

``During Northridge, they had to wait for the sun to come up and fly helicopters to find out where the damage was,'' Jones said. ``Instead of waiting until 6:30 a.m., next time there would be a map at the fire station at 4:44 a.m. showing, 'This is probably where the worst damage is.'

``After Northridge, it took one or two months to get an accurate picture of the ground shaking. Now we have a system that is connected to modern communications. That has been the biggest change - and the most exciting.''

The system, a joint effort by Caltech, the U.S. Geological Survey and the California Division of Mines and Geology, proved its importance during the 7.0-magnitude Hector Mine earthquake on Oct. 16, 1999. Within two minutes, officials had maps in hand showing where the ground had shaken the hardest.

``It allowed everyone to see first-hand where they needed to send search-and-rescue teams,'' said Egill Hauksson, a senior research associate in geophysics at Caltech.

For people who are miles away from the epicenter, scientists are looking into the possibility of an automated warning system that could send out alerts.

``You might be talking about five, 10 or 15 seconds of warning time,'' Hauksson said. ``If the quake happened in Palm Springs, it may take 40 seconds before strong ground shaking gets to Los Angeles. Our goal is to be able to issue some kind of alert.''

The Southern California system is being expanded statewide and the federal government is interested in a $170 million expansion nationwide.

``This is a huge improvement in the state's capacity to support local governments,'' said Richard Eisner, regional administrator for the Governor's Office of Emergency Services.

``It's backed up by a state-owned satellite computer system. Even if we lose the phone system, we can communicate across the state and move mutual aid assistance to any jurisdiction. We're talking about the National Guard, aircraft, trucks, water, search and rescue teams and conservation corps volunteers. If they need firefighters, we can call up firefighters from across the state.''

Los Angeles Fire Department Capt. Stephen Ruda said the biggest advance since the 1994 quake is a coordinated disaster plan among government agencies. And hundreds of residents have been trained as part of the Community Emergency Response Teams to help during natural disasters.

``You can have all the sophisticated equipment that is necessary, but it will still take a young firefighter or that CERT member to stand on that pile of rubble and do what is needed to protect lives and property,'' Ruda said.

Carol Gunter, assistant director of the county Emergency Medical Services Agency, said the technological advances will improve the information available during the next earthquake.

In a disaster, her office coordinates the medical response in conjunction with the county Emergency Operation Bureau, under the direction of Sheriff Lee Baca.

``Until you actually see what is going on, a shake map doesn't really tell you everything,'' Gunter said. ``It doesn't tell you what happened to a structure or how many people were injured.''

While earthquake technologies have improved in the past eight years, experts say only a small percentage of buildings in the Los Angeles region meets the newest earthquake codes because code improvements are not retroactive.

Given the potential of an 7.0-magnitude-or-greater earthquake on the Elysian Park Fault beneath downtown Los Angeles, experts say they are concerned about the county's thousands of steel-frame buildings, some of which sustained weld fractures in 1994.

``It's a serious matter because the ground could shake harder in a future earthquake and just because something survived Northridge doesn't mean it will survive a future quake,'' said John Hall, professor of civil engineering at Caltech.

An even more serious issue is the county's thousands of concrete buildings, as well as multiple-story condominiums and apartment buildings with underground parking structures. Sixteen people died when one of those complexes, Northridge Meadows, collapsed during the 1994 quake.

``We haven't been able to do anything about the existing building stock even though we know this is hazardous,'' Hall said. ``The cities have not passed ordinances to require retrofits.''

Looking at the 23-year span between the 6.5-magnitude Sylmar Quake on Feb. 9, 1971, and the 1994 Northridge Earthquake, Hauksson said it's not unreasonable to expect a significant earthquake every 20 years in Southern California.

Los Angeles County is located in one of the world's most seismically active areas, with a historical record of major earthquakes occurring about seven times each century.

The last great California earthquake occurred Jan. 9, 1857, when a 8.3- magnitude quake along the mighty San Andreas Fault struck Fort Tejon. Before that, it was only 45 years to the previous earthquake along the San Andreas, the 1812, 7.0-magnitude temblor in San Juan Capistrano.

``The largest interval was 350 years around the year 1200,'' Jones said. ``It averages around 150 years. Maybe we're in one of those 350-year intervals or maybe we're in a 146-year interval and it will be this year.

``The annual chance of a San Andreas earthquake is about 1 percent. There is nothing going on to make me think that is higher.''

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3 photos

Photo:

(1 -- color) A vintage car sits crushed under a downed apartment building following the 1994 Northridge Earthquake.

John McCoy/Staff Photographer

(2 -- 3 -- color) A gas fire burns on Balboa Boulevard in Granada Hills on the morning of Jan. 17, 1994, hours after the Northridge Earthquake. An officer surveys the scene at the intersection of the Antelope Valley and Golden State freeways hours after the 1994 Northridge Earthquake.

Gus Ruelas/Staff Photographer