Earthquake research at Parkfield; 1993 and beyond report of the National Earthquake Prediction Evaluation Council (NEPEC) Working Group to evaluate the Parkfield Earthquake Prediction Experiment

Abstract. The local "when" for earthquake prediction is based on the connection between geomagnetic "quakes" and the next incoming minimum or maximum of tidal gravitational potential. The probability time window for the predicted earthquake is for the tidal minimum approximately ±1 day and for the maximum ±2 days. The preliminary statistic estimation on the basis of distribution of the time difference between occurred and predicted earthquakes for the period 2002-2003 for the Sofia region is given. The possibility for creating a local "when, where" earthquake research and prediction NETWORK is based on the accurate monitoring of the electromagnetic field with special space and time scales under, on and over the Earth's surface. The periodically upgraded information from seismic hazard maps and other standard geodetic information, as well as other precursory information, is essential.

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Seismicity alert probabilities at Parkfield, California, revisited

Bulletin of the Seismological Society of America ◽

10.1785/bssa0880010117 ◽

1998 ◽

Vol 88 (1) ◽

pp. 117-130

Author(s):

Andrew J. Michael ◽

Lucile M. Jones

Keyword(s):

Uniform Distribution ◽

Earthquake Prediction ◽

Confidence Level ◽

San Andreas Fault ◽

Strike Slip ◽

San Andreas ◽

Background Seismicity ◽

Parkfield Earthquake ◽

The U.S

Abstract For a decade, the U.S. Geological Survey has used the Parkfield Earthquake Prediction Experiment scenario document to estimate the probability that earthquakes observed on the San Andreas fault near Parkfield will turn out to be foreshocks followed by the expected magnitude 6 mainshocks. During this time, we have learned much about the seismogenic process at Parkfield, about the long-term probability of the Parkfield mainshock, and about the estimation of these types of probabilities. The probabilities for potential foreshocks at Parkfield are reexamined and revised in light of these advances. As part of this process, we have confirmed both the rate of foreshocks before strike-slip earthquakes in the San Andreas physiographic province and the uniform distribution of foreshocks with magnitude proposed by earlier studies. Compared to the earlier assessment, these new estimates of the long-term probability of the Parkfield mainshock are lower, our estimate of the rate of background seismicity is higher, and we find that the assumption that foreshocks at Parkfield occur in a unique way is not statistically significant at the 95% confidence level. While the exact numbers vary depending on the assumptions that are made, the new alert probabilities are lower than previously estimated. Considering the various assumptions and the statistical uncertainties in the input parameters, we also compute a plausible range for the probabilities. The range is large, partly due to the extra knowledge that exists for the Parkfield segment, making us question the usefulness of these numbers.

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