History, Description & Funding

History of TriNet

Southern California is unique because it is one of the few places on earth where a plate boundary extends across the continental crust rather than on the ocean floor. Because earthquakes are concentrated along plate boundaries, California has alot of earthquakes. California also has a large population, and the areas of highest population density are all near the San Andreas fault, the major boundary between the North American and Pacific Plates, which extends along the length of California.

Each day there are about 30 earthquakes recorded in southern California, although most are too small to be felt. A typical year produces over 10,000 earthquakes. The most recent significant earthquake in southern California was the magnitude 6.7 Northridge earthquake on January 17, 1994. Because of its location in a highly populated urban area with a high density of seismographs, it is the most well-recorded and thoroughly-studied earthquake ever. The last great earthquake in southern California was the magnitude 7.9 earthquake in 1857 that ruptured the southern section of the San Andreas Fault. Sometime in the future, there will be another great earthquake like it in southern California.

The three partner agencies in TriNet - The California Institute of Technology ( Caltech), the U.S. Geological Survey (USGS), and the California Geological Survey (CGS) - have been operating separate seismic networks for many years. Since the 1960's the Caltech Seismological Laboratory, in collaboration with the USGS, has operated a telemetered analog seismic array in southern California. With more than 200 remote stations, this array, the Southern California Seismic Network (SCSN) has been the major source of earthquake information in southern California and is used to advise more than a dozen governmental agencies, including California Office of Emergency Services in Sacramento, the Los Angeles County Emergency Information Bureau, the Pacific Tsunami Warning Network, the Office of Emergency Preparedness, and electric, gas, and transporation utilities. The SCSN earthquake catalog is one of the most complete earthquake catalogs in the world with over 344,000 events starting in 1932. The SCSN also provides digital waveforem data, phase arrival data, and first motion data at all timed stations for each recorded earthquake.

The USGS also operates the National Strong Motion Program (NSMP) network which consists of 571 seismic stations nationwide that record strong ground motions.

CGS operates the California Strong Motion Instrumentation Program (CSMIP) network consisting of well over 400 analog strong motion sensors in California. CMDG provides waveform data sets after significant earthquakes.

In late 1987, the TERRAscope project began, and presently 19 digital TERRAscope stations have been installed in southern California. To facilitate real-time distribution of earthquake data, Caltech and the USGS, in cooperation with corporate partners, started the Caltech US Geological Survey Broadcast of Earthquakes (CUBE) project in 1990. Also, in 1990 the Southern California Earthquake Center (SCEC) Data Center opened at Caltech. The SCEC Data Center provides earthquake data to researchers over the internet.

Then in 1994 the California Research and Education Network (CalREN) grant program, funded by Pacific Bell, provided a grant to connect remote digital seismographic stations to a central site, Caltech in Pasadena, for real-time monitoring of earthquake activity in southern California. The project's objective was to demonstrate the increased speed and accuracy of earthquake information that can be provided with a fully digital network. TERRAscope, provided the digital signals that were being transmitted to Pasadena using new digital data transmission technologies.

In 1994, Caltech and Kinemetrics Inc. were funded to begin the Automated Strong Motion Monitoring Program (AMOES) that consisted of developing the K2 and installation of 16 K2 instruments in the greater Los Angeles region.

TriNet was funded in 1997 to create a better, more effective real-time earthquake information system for southern California. Caltech, USGS, and CGS are leveraging their resources with private partners to improve the current system, building on the strengths of TERRAscope.

TriNet will incorporate new technologies enabling a much greater bandwidth and dynamic range to provide accurate and vital information within minutes of an earthquake. Our goal is to mitigate the impact of future large earthquakes in Southern California. Caltech's Seismological Laboratory and the USGS are reconfiguring and modernizing Southern California's existing seismic network, the Southern California Seismic Network (SCSN), with real-time transmissionand processing capability and new digital instruments at 200 sites. CGS will upgrade and expand strong motion instrumentation at 400 sites in their existing California Strong Motion Instrumentation Program (CSMIP) network and the USGS National Strong Motion Program (NSMP) will upgrade 35 of their current southern California sites to retrieve near real-time ground motion parameters and collect data from improving building codes.

TriNet Description

The TriNet system includes two types of sensors:

Signals from the seismic stations are transmitted to the central processing facility at Caltech via digital phone lines (frame relay), radios, microwave links, and the Internet. The seismic data are analyzed immediately to answer the important questions: Where did the earthquake occur? How big was it? What was the distribution of shaking? What fault did it occur on? What was the type of faulting? The information will then be available through the Internet and sent directly to cost-sharing partners through a commercial paging system or a secure Intranet.

TriNet products include:

  • Emergency Response
    TriNet is able to rapidly advise the media, government agencies, disaster response teams, and the utilities so that informed decisions may be made as to where to dispatch personnel and equipment after a damaging earthquake. Another TriNet goal is to provide training for emergency managers and earthquake engineers to facilitate the efficient use of TriNet products. All of the TriNet data are available through the Internet at this website. In addition, Caltech/USGS Broadcast of Earthquakes (CUBE) project is distributing TriNet information rapidly to Caltech's Earthquake Research Affiliates, providing user support and improving real-time distribution. The Southern California Earthquake Center (SCEC) Data Center is providing a long-term data archive, accessible over the Internet.

  • Research The automatically broadcasted information and other data are used by scientists to assess the status of seismic activity on a daily basis. The high quality and high density of digital data will enable more accurate and detailed studies of earthquake hazards, seismotectonics, crustal velocities, source processes, and characteristics of the interior of the earth, among many other important research topics.

  • Pilot Seismic Computerized Alert Network (SCAN) Pilot seismic computerized alert network is an emerging technology that will provide the capability to recognize and send notification that an earthquake is in progress before shaking from that event arrives at a distant site. Such alerts may provide a lead time of seconds to several tens of seconds before the most damaging shaking arrives. Some potential uses for computerized alerts are stopping trains, protecting fragile facilities, interrupting handling of toxic chemicals, securing power supplies, databases, and bringing elevators to the closest floor. We are prototyping the technology, although the present capabilities do not include the robustness and backup systems necessary to make this a viable system.

Below is a graphic representation of the TriNet layout. Note that there are multiple methods for data retrieval from seismic stations. Once the information arrives at the central processing site many different automated operations are performed, including event data storage, event identification and processing, and user notification.


Major funding has been provided by:

California Geological Survey
California Governor's Office of Emergency Services
California Institute of Technology
Federal Emergency Management Agency
United States Geological Survey

Additional contributions:

Ida H.L. Crotty
Donna & Greg Jenkins
Southern California Edison
Sun Microsystems Inc.

This page is www.trinet.org/trinetdesc.html. Last updated 02/08/01. Designed and maintained by Lisa Wald.
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