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Study on the New Method of Determining the Types of Small Earthquake Swarms

Author: CuiZiJian
Tutor: LiZhiXiong
School: China Seismological Bureau, Institute of Earthquake Prediction
Course: Solid Geophysics
Keywords: Prediction of earthquake physics Type of earthquake swarms Focal mechanism Similarity Spectral amplitude correlation
CLC: P315
Type: Master's thesis
Year: 2011
Downloads: 33
Quote: 0
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Abstract

General small earthquakes in seismic activity of small earthquakes occur frequently, its rapid discrimination of possible types, that are activities in small earthquake swarm, whether earthquake foreshock sequence, or not accompanied by the earthquake occurred fast determination of the group, has important practical significance for the reduction of earthquake disasters and safeguarding social stability. Around the research carried out by small earthquake swarm sequence type discriminant recent decades, has made a lot of progress, a certain effectiveness of the various methods are shown in the practical application of earthquake prediction, but most of the methods are statistical in nature, according to their discrimination made varying degrees of uncertainty is inevitable. Therefore, it is necessary in many ways to study and explore the physical meaning more clear, more effective results, the new discrimination method. Existing theory and earthquake case study shows that, compared with the general small earthquake swarm, foreshock sequences the focal mechanism tends to be more consistent. In view of the small earthquake focal mechanism is not easy solving this study, the introduction of the spectral amplitude analysis method to study the small earthquake focal mechanism, in order to explore the possibility of a small earthquake swarm sequence type determination. Its overall scientific idea is deducted, the observed displacement spectra of each earthquake earthquake swarm propagation path effect, station site effects and other factors, the spectral amplitude, focal mechanism is similar to the problem described by the correlation coefficient calculated spectral amplitude . Spectral amplitude correlation coefficient close to 1, indicating that the earthquake swarms various small earthquake focal mechanism similar judgment foreshock sequences likely; Conversely, the lower the degree of similarity of various small earthquake focal mechanism, determine for general small earthquake swarm may is greater. As a test of theoretical deduction, select three accompanied the earthquake occurred and the three after a small earthquake swarm is not associated with the earthquake occurred, the correlation coefficient were calculated spectral amplitude of the earthquake swarm sequence. The results show that, Liaoning Xiuyan 5.4 earthquake of November 29, 1999, April 12, 2001 before Yunnan the Shidian 5.9 earthquake and Yongsheng 6.0 earthquake, before October 27, 2001, in the future, \focal area or the edge of a small earthquake swarm occurred, spectral amplitude correlation coefficient is average or minimum value above 0.85, close to 1; Yunnan January 2002 Yangbi Eryuan November 2003 to December 2005 5 to 6 months after the Binchuan three is not associated with the general small earthquake swarm earthquake occurred, whether average or maximum value of less than 0.80 (the average is less than 0.70), significantly less than 1. The experimental results and the theoretical deduction coincides mean spectral the amplitude correlation analysis to distinguish a small earthquake swarm may be a more specific type of a physical meaning, better performance of the new method. In addition, in the above calculation process, the study also inversion Liaoning Xiuyan and northwestern Yunnan region of the P-wave and S-wave Q values, as well as the station's site effects. In this study, the parameters of the \The study shows that the information collected on this article, under the guidance of some theoretical models seismological parameters (spectral amplitude correlation coefficient method) to identify the type of earthquake swarms performance than traditional statistical analysis methods to predict high-performance, indicating that seismic waves The data carried the seismogenic information should be more than rich in earthquake directory information. The study concluded that, as long as a small earthquake swarm around a number of digital seismic stations recorded small earthquake swarm sequence of spectral amplitude correlation coefficient can be determined, the spectral amplitude analysis has application value, and worthy of further study.

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