IEEE Computer Volume 11 Number 6 -- NEW APPLICATIONS
Original Publication Date: 1978-Jun-01
Included in the Prior Art Database: 2005-Nov-10
Software Patent Institute
Prof. D. A. Michalopoulos: AUTHOR [+3]
THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.
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Prof. D. A. Michalopoulos
California State University, Fullerton
Computers aid Caltech earthquake research
A computer now watching over Cal tech's extensive network of seismometers allows seismologists a faster, more pre" else look at southern California's earthquake activity, a Caltech seismologist reported last week.
Carl Johnson, a graduate student who developed the system, said that the computer allows records of seismic events to be made available far more quickly than with previous manual systems using paper and photographic film. Such rapid availability of seismic records enables researchers to study earthquake activity as it occurs.
Called the Caltech Earthquake Detection and Recording System, it is the only one of its kind currently operating in this country. The CEDAR System monitors the Caltech/US Geological Survey network of 148 seismometers in southern California via phone lines, and records data from the seismometers only when the system detects the evidence of an earthquake.
The system began operation last year and consists of two computers. A Data General Nova 820 monitors the seismic network, examining incoming signals from each station 50 times per second, and determines whether the signals India cate an earthquake. Should several neighboring stations detect possible earth. quake motions, the computer saves the data on digital magnetic tape. A Data General Eclipse S/230 assists data analysis; scientists can examine and analyze the seismic traces on a Tektronix 4014 graphics terminal or can work with printouts.
Because seismologists would rather record signals from such nomseismic sources as rumblings from passing trucks than miss an earth tremor, the CEDAR System is programmed to be cautious
about rejecting data. Upon closer inspect tion, according to Johnson, only 40 percent of the events recorded by the com puter turn out to be earthquakes. Never" theless, he said, the computer rejects 99.9 percent of the background signals from the stations as void of earthquakes, enormously reducing the load of information with which the seismologists must deal.
The system has proved to be more thorough and precise in its data recording than previous methods It has detected about 20 percent more earthquakes than the previous method of visually scanning miles of paper tracings. Johnson is using the improved data to study patterns in the swarms of tiny tremors in California's Imperial Valley.
IEEE Computer Society, Jun 01, 1978 Page 1 IEEE Computer Volume 11 Number 6, Pages 101-118