TriNet, Caltech/USGS Element: The New Digital Real-Time Earthquake Monitoring System for Southern California

E Hauksson, H Kanamori, R Clayton, and T Heaton (Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125)

J Mori, and L Jones (US Geological Survey, 525 S. Wilson Av., Pasadena, CA 91106)

TriNet is a cooperative project between Caltech, USGS, and CDMG to build the new digital real-time ground motion monitoring system for southern California. The major goals of this project are to upgrade: 1) existing stations in the Southern California Seismographic Network from narrow band to broad-band sensors and to provide real-time digital dedicated communications; and 2) existing CDMG strong motion instruments from analog to digital and to add near-real-time communications. In some cases old sites may be terminated and new sites installed. TriNet products, derived from data from both Caltech/USGS and CDMG stations, will provide earthquake information for quick emergency response and a data base of strong ground motion for long-term mitigation purposes.

The Caltech/USGS element of TriNet is focused on developing a state-of-the-art real-time earthquake monitoring system for both small and large earthquakes. The objectives are: 1) to continue the production of the southern California earthquake catalog, which requires a data processing facility capable of processing 35,000 events per year; 2) to provide data onscale for earthquakes of all sizes; and 3) to enhance the capability to distribute earthquake information in near-real-time.

The new digital seismographic stations will have both weak and strong motion 3-component sensors with 24 bit digitizers. The remote stations will use ethernet connectivity to communicate to the central site at Caltech in Pasadena, using Frame Relay packet communications. The ethernet connectivity will make multiple data streams from each station available to different hosts, and will allow us to operate the seismographic network as a distributed computer network. At the central site we are developing real-time data acquisition software that allows both routine and research processing of the data. This software will use computers with multiple processors to facilitate real-time processing of the digital data streams. The routine processing will consist of determining point and finite source parameters and the geographical distribution of ground shaking, a joint Caltech/USGS and CDMG project referred to as ShakeMap. The research processing of the data will depend on the interests of individual researchers and may include development of new software, for instance, for source quantification or detection of slow earthquakes. TriNet products such as source parameters, and ShakeMap will be distributed electronically via CUBE paging broadcasts, Internet, dedicated digital phone lines, and other means. The future goals of TriNet are to provide early warning of impending strong shaking to facilities located outside the source region, when a major earthquake occurs in southern California.

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