地震学报（英文版）2004，Vol.17Issue(2)：152-163,12.
Study on medium-short term earthquake forecast in Yunnan Province by precursory events
Study on medium-short term earthquake forecast in Yunnan Province by precursory events
摘要
Abstract
The medium-short term forecast for a certain kinds of main earthquake events might be possible with the time-to-failure method presented by Varnes (1989), Bufe and Varnes (1993), which is to simulate an accelerative releasing model of precursory earthquake energy. By fitting the observed data with the theoretical formula, a medium-short term forecast technique for the main shock events could be established, by which the location, time and magnitude of the main shock could be determined. The data used in the paper are obtained from the earthquake catalogue recorded by Yunnan Regional Seismological Network with a time coverage of 1965～2002. The statistical analyses for the past 37 years show that the data of M≥2.5 earthquakes were fairly complete. In the present paper,30 main shocks occurred in Yunnan region were simulated. For 25 of them, the forecasting time and magnitude from the simulation of precursory sequence are very close to the actual values with the precision of about ±0.57(magnitude unit). Suppose that the last event of the precursory sequence is known, then the time error for the forecasting main shock is about ±0.64 year. For the other 5 main shocks, the simulation cannot be made due to the insufficient precursory events for the full determination of energy accelerating curve or disturbance to the energy-release curve. The results in the paper indicate that there is no obviously linear relation in the optimal searching radius for the main shock and the precursory events because Yunnan is an active region with damage earthquakes and moderate and small earthquakes. However, there is a strong correlation between the main shock moment and the coefficient k/m. The "optimal fitting range" for the forecasting time and magnitude can be further reduced using the relation between the main shock moment lgM0 and the coefficient lgk/m and the value range of the restricting index m, by which the forecast precision of the simulated main shock can be improved. The time-to-failure method is used to fit 30 main shocks in the paper and more than 80% of them have acquired better results, indicating that the method is prospective for its ability to forecast the known main shock sequence. Therefore, the prospect is cheerful to make medium-short term forecast for the forthcoming main shocks by the precursory events.关键词
time-to-failure method/precursory event/energy accelerating curve/medium-short term forecast/Yunnan regionKey words
time-to-failure method/precursory event/energy accelerating curve/medium-short term forecast/Yunnan region分类
天文与地球科学引用本文复制引用
秦嘉政,钱晓东..Study on medium-short term earthquake forecast in Yunnan Province by precursory events[J].地震学报（英文版）,2004,17(2):152-163,12.基金项目
Scientific and Technological Key Project of Yunnan Province (No. 2001NG46) and State Key Basic Research Development and Programming Project of China (No.95130505). （No. 2001NG46）
