Simulating a Large Wasatch Front, Utah, Earthquake Using Small Earthquake Recordings as Green's Functions.
Environmental research papers Sep 83-Oct 85,
AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA
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Several earthquake recordings at Golden, Colorado in the magnitude ranges 4-6, were digitized and were used to investigate the feasibility of adding them together to simulate a larger earthquake magnitude 7.0-7.5. The test path of the Wasatch Front, Utah, to the WWSSN station at Golden was selected distance 400 - 500 km. The hypothetical causative fault was given dimensions on the order of 45 km long by 20 km wide and was divided into cells, representative in size to the seed events rupture dimensions and with other variations. The results were evaluated by total energy and amplitude criteria. The final waveforms were judged to be adequate predictions at the lower frequency end of the spectra. The high frequency content was controlled by the spectra of the seed earthquakes whose magnitudes were too large to adequately reproduce the Greens function response at these frequencies. It is recommended that this technique be used at smaller distance ranges or at stations whose sensitivity is set high enough so as to record the smaller magnitude earthquakes, more representative of impulse responses at all frequencies. Keywords Seismic waves Seismic data Synthetic waveforms Greens function addition Wasatch front earthquake Seismic hazard Earthquake prediction.