Journal of Conference Abstracts

Magnitude 8.0 and Above Earthquakes, 1985-1997, Prove Statistical Significance of an Earthquake Prediction Method

Vladimir G Kossobokov (volodya@ipgp.jussieu.fr)¹, Vladimir I Keilis-Borok (kborok@cyclop.ess.ucla.edu)¹ & John H Healy (jhhealy@aol.com)²

¹IIEPT&MG, Warshavskoye Sh, 79-2, Moscow, 113556, Russia

²USGS, 345 Middlefield Rd, Menlo Park, CA, 94025, U.S.A.

Statistical significance above 99% level is established for prediction of earthquakes by the algorithms M8 and "Mendocino Scenario," MSc. This evaluation is based on the results of a real-time intermediate-term prediction of the largest earthquakes in Circum Pacific and its surroundings, specifically, in overlapping circles which scan near-uniformly the territory considered.

We use the earthquake catalog taken from the National Earthquake Information Center Global Hypocenters Data Base. The completeness of the catalog is sufficient for application of M8 in 90% of the belt. The M8 alarms cover on average 31% of its length at any given time, while MSc reduces this number to 9%.

All the seven earthquakes of magnitude 8.0 or greater are predicted by M8 and only one of them is missed in the second approximation given by MSc. We distinguish the two intervals, 1985-1997 and 1992-1997: Since 1985 the data base becomes sufficient for prediction considered, and in 1992 the data base was formally set up along with the procedure of its updating (Healy et al., 1992).

Both algorithms provide intermediate-term prediction based on seismicity patterns. Alarms, determined by M8, cover several years and territory up to (5~10)L in linear dimension, L being the length of the source of an expected large earthquake. MSc provides a second approximation reducing this territory to (1~3)L. Such predictions allow to prevent a considerable part of damage by escalation of inexpensive intermediate-term safety measures.

Statistical validity of predictions confirms the underlying paradigms: (i) large size of the fault system involved in formation of earthquake precursors; (ii) existence of a premonitory rise and clustering of seismicity; (iii) partial similarity of these phenomena in a wide range of tectonic environment.

Short-term precursors close to the source of the approaching strong earthquake are identified within time-space of intermediate-term alarms.

Healy et al., USGS OFR-92-401, (1992).