Seismic net makes quake visual

The California Integrated Seismic Network pools data to produce color-coded digital maps of earthquakes minutes after they occur.

The 1989 magnitude 7.1 Loma Prieta earthquake in California was one of the most televised earthquakes ever. More than 62,000 baseball fans filled San Francisco's Candlestick Park for the third game of the World Series as the ground began to shake.

'All the news cameras were focused there in San Francisco,' said Tony Shakal, a seismologist with the California Conservation Department. 'But the strongest shaking was more than 60 miles away in Santa Cruz,' he said. 'Nobody knew that at first. Everybody was looking at San Francisco.'

It took officials two days to determine the extent of the damage. Part of the problem was California's system of seismic monitoring, which was fragmented into regional agencies. Sixty-two people died in the quake, and damage to homes and businesses amounted to $10 billion. 'Too much of the information was anecdotal. We needed real quantitative knowledge,' Shakal said.

Gov. Gray Davis announced this spring the allocation of $2.9 million to form the California Integrated Seismic Network, which will integrate and expand existing regional earthquake monitoring networks.

Group effort

Several organizations collaborate on CISN, including the Berkeley Seismological Laboratory, U.S. Geological Survey, Caltech Seismological Laboratory, California Geological Survey and Governor's Office of Emergency Services, the lead agency on the project.

Each of these seismic networks has a slightly different mission, said David Oppenheimer, a seismologist with USGS. Some monitor structures or ground motion. Others perform seismic research. 'If we can pull all this together, we can start to use the network for real-time emergency response activities,' Oppenheimer said.

The disparate seismic networks each use their own software, Oppenheimer said. USGS is working on a public-domain software effort called Earthworm, Oppenheimer said. The agency is working to link as many seismic networks as possible through the software, which was written in C by USGS programmers. CalTech programmers developed their own seismic software called RogueWave, written in C++. Both Earthworm and RogueWave work with Oracle Corp. database management systems.

Even the agencies' operating systems vary. Berkeley and CalTech run Sun Microsystems Solaris on Sun machines. California and USGS run their systems on Microsoft Windows NT. The agencies all use different seismic instruments, too. Data comes in from satellites and over digital subscriber lines, frame relay and dial-up connections.

CISN officials will produce ShakeMaps, digital maps that use a color scheme to show the intensity surrounding the epicenter of an earthquake. Organizations can download ShakeMaps and add their own data. ShakeMap users include public-safety officials, emergency response workers and construction engineers.

ShakeMaps 'show us immediately where the most serious shaking has occurred and allow us to quickly dispatch crews to where they are needed most,' said Dallas Jones, director of the Office of Emergency Services.

Shakal's department sends data to ShakeMaps from sensors in the field that transmit seismic data over a primitive operating system'more limited than MS-DOS, Shakal said'to a bank of computers in Sacramento. The maps can be generated and posted on the Internet within four to six minutes after an earthquake.

The state has come a long way in sharing seismic information since the 1989 quake and the 1994 magnitude 6.7 Northridge quake. 'If a Northridge-sized quake were to happen tomorrow, and the Internet stayed operational through it, you would see a marked improvement in response and quantity of information,' Oppenheimer said.

About the Author

Trudy Walsh is a senior writer for GCN.

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