| Study on medium-short term earthquake forecast in Yunnan Province by precursory events |
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| 作者姓名： | 秦嘉政 钱晓东 |
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| 作者单位： | Earthquake Administration of Yunnan Province，Kunming 650041，China，Earthquake Administration of Yunnan Province，Kunming 650041，China |
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| 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). |
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| 摘 要： | Introduction Yunnan is a very active region of earthquake in China. Since Yunnan Regional Seismological Network established in 1965, 37 years have past and thousands of seismic events have been recorded. Among them, 9 are great earthquakes of M7.0, more than 150 are moderately strong earthquakes of M =5.0~6.9 and about 6 000 are earthquakes of M3.0. Figure 1 shows the epicenter distribution of M3.5 earthquakes occurred in 1965~2002 in Yunnan region and Figure 2 the magnitude-frequency dis…
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| 收稿时间： | 6 December 2002 |
| 修稿时间： | 24 April 2003 |
Study on medium-short term earthquake forecast in Yunnan Province by precursory events |
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| Qin Jia-zheng and Qian Xiao-dong.Study on medium-short term earthquake forecast in Yunnan Province by precursory events[J].Acta Seismologica Sinica(English Edition),2004,17(2):152-163. |
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| Authors: | Qin Jia-zheng and Qian Xiao-dong |
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| Institution: | Earthquake Administration of Yunnan Province, Kunming 650041, China |
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| 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 ofM≥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 coefficientk/m. The “optimal fitting range“ for the forecasting time and magnitude can be further reduced using the relation between the
main shock moment lgM
0 and the coefficientlgk/m and the value range of the restricting indexm, 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.
Foundation item: Scientific and Technological Key Project of Yunnan Province (No. 2001NG46) and State Key Basic Research Development and
Programming Project of China (No. 95130505). |
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| Keywords: | time-to-failure method precursory event energy accelerating curve medium-short term forecast Yunnan region |
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