In 1989, a 7.1 earthquake shook the San Francisco Bay Area, causing the Bay Bridge to sever, the Nimitz freeway to collapse, and the ground beneath the Marina District to liquefy – all in just 15 seconds.
Scientists predict that there is a 70 percent chance that an earthquake of at least 6.7 magnitude will rock the Bay Area before 2030. With those odds, in a state lined with hotbeds of seismic activity, preparedness is critical.
Last week, California Gov. Gray Davis announced a new statewide seismic monitoring network, the California Integrated Seismic Network (CISN).
Davis' $2.9 million project will integrate and expand existing regional earthquake monitoring networks, a plan designed to speed emergency response to devastating earthquakes.
Members of the CISN include the California Geological Survey, Caltech Seismological Laboratory, Berkeley Seismological Laboratory, USGS Menlo Park and USGS Pasadena.
"The real application here is being able to see at a glance how large a disaster is and whether to call on 10 police officers, 100 police officers or 1,000 police officers," said Lind Gee, a seismologist at the University of California at Berkeley. "The sooner you have the information, the better off you are."
Until recently, seismic monitoring in Northern and Southern California was fragmented into separate regional agencies, resulting in delayed earthquake-response information. Seismologists were equipped predominantly with 1960s-era analog seismic instruments that stymied them from deploying data quickly.
All that changed when a 6.7 magnitude earthquake rocked Southern California in 1994.
"The Northridge quake showed all the problems that could happen with older instrumentation," Gee said.
In both the 1989 Loma Prieta earthquake and the Northridge quake, it took up to two days for authorities to determine the extent of the damage.
After the Northridge quake, funding of the TriNet collaborative monitoring project in Southern California created a new emergency response product, "ShakeMaps."
Real-time ShakeMaps use a color scheme to map the intensity surrounding the epicenter of an earthquake. These maps show where the most serious shaking has occurred, so emergency response teams can focus their efforts where they are needed most.
ShakeMaps can be generated within four to six minutes after an earthquake occurs. The maps can be continuously updated with additional data as it is released.
"(ShakeMaps) really convinced emergency-response people that seismic monitoring could really help them and could really make a difference," Gee said.
CalTrain can use the maps to decide whether or not to stop a train, depending upon where an earthquake is located. PG&E, a California utility, can use them to decide whether to deploy response teams.
Recent technological advances, along with decreased telecommunication costs, have made it possible to integrate existing, separate networks and share data inexpensively.
In the past, if communication links and power failed, data would be irretrievably lost. Today, data from seismic sensors are digitized on site with modern broadband seismometers that can record a full range of ground motions, from small to large earthquakes. The data is recorded locally on disk and transmitted over dedicated communication links to monitoring facilities.
"Now you can get an accurate magnitude quickly," said Caltech seismologist Egill Hauksson.
Although modern instruments have increased response times, technology has yet to be developed that will predict earthquakes before they occur.
"We can't predict earthquakes, but we do know how to locate them once they occur," Gee said. "Once an earthquake occurs, we can tell you about it."
"Prediction has been a Holy Grail for a number of years," Gee said. "Unfortunately, we haven't developed that capability yet. At this point, there are no clear-cut tools, no clear-cut mechanisms that we fully understand (to make predictions)."
The CISN will establish two processing centers, which will each locate earthquakes across the state. So if a major temblor hits the Hayward fault and UC Berkeley's facility is damaged, seismologists at Caltech will be able to provide the same ShakeMap data.
This robust "T1 ring" will allow the monitoring centers to be able to function independently even if the Internet goes down.
"Our efforts are very vulnerable to a damaging event in our own backyard," Gee said. "We don't want to be dependent on a single point of failure."
CISN's data will likely help engineers build safer, stronger structures, seismologists agree.
"The more data we record, the more projects (will be developed) to improve building codes and structural design," Gee said.
While scientists have been measuring seismic activity for decades, only recently have modern instruments been introduced that can help speed response times.
"We can still use data (after an earthquake occurs) to improve building codes, but the real step forward is that we can also use this data to improve emergency response," said Tony Shakal, of the California Geological Survey.
These new instruments have dynamic range and resolution so seismologists can measure even low levels of shaking and calculate frequencies shortly after earthquakes occur.
"Now we can convert raw measured data into useable information about shaking to understand the impact for a structure," Shakal said. "Five years ago it was not possible to do this."
CISN will likely serve as a model and will be part of the Advanced National Seismic System, a federal effort to modernize instruments and coordinate earthquake monitoring across the nation.
"California has been on the leading edge of seismic monitoring," Gee said. "We have the earthquakes and we have the population."
But California isn't alone in its earthquake risk. Just two weeks ago, a 5.0 earthquake shook New York.
"While California has the leading risk, earthquake hazard exists in any state," Gee said.
