ANALYSIS OF SEISMICITY CHANGES PRIOR TO THE 2014 YUNNAN JINGGU MS6.6 EARTHQUAKE

doi:10.3969/j.issn.0253-4967.2016.04.021

Abstract

Abstract:

According to the Region-Time-Length (RTL) algorithm,the analysis of seismicity changes prior to the 2014 Yunnan Jinggu M_S6.6 earthquake was conducted by using the earthquake catalogues about 6 and 15 years before this earthquake,respectively.When the studied period was nearly 6 years,an enhancement of seismic activity was detected around the epicenter since the beginning of 2013.The anomalies mainly distributed in the region of 22.5°~24.5°N and 99°~102°E.The range and degree of anomalies changed from small to large,and then to small chronologically.As the surface integral in respect to RTL,the physical parameter I_RTL,which could reflect the regional seismicity level,began to increase since August 2013,and then reduced after reaching the peak point.The time length from the peak point of I_RTL curve to the earthquake occurrence was 9 months.When the analyzed catalogue was nearly 15 years,the 2007 Ninger M_S6.4 occurred in the studied region.Seismicity quiescence was detected prior to the Ninger M_S6.4.Before the Jinggu M_S6.6,seismicity quiescence was detected firstly,and then enhanced activity was observed 1 year prior to the earthquake occurrence.The anomalies mainly distributed in the region of 22.5°~24.5°N and 99°~102°E.The time length from the peak point of I_RTL curve to the earthquake occurrence was 7 months.The above study showed that even the earthquakes location was near and the magnitude was close to each other,a big difference in seismic activity before the earthquakes may exist.Before the Jinggu M_S6.6,there was some difference in seismicity changes according to different beginning time of catalogues,but the distribution of anomalies and the time length from the peak point of I_RTL to the earthquake occurrence were uniform.So there was an important significance for exploring the relationship between the distribution of anomalies and the earthquake location,and the relationship between the time of the peak point of I_RTL and the earthquake occurrence time.

Key words: Region-Time-Length(RTL)algorithm, surface integral of RTL, Jinggu earthquake, seismic hazard evaluation

摘要：

基于Region-Time-Length（RTL）算法，使用震前约6a和15a的地震目录定量检验了2014年景谷M_S6.6地震前的地震活动变化。研究时段近6a的分析结果显示：自2013年初在震中附近检测到地震活动增强，空间异常分布在22.5°~24.5°N，99°~102°E内，异常范围和异常程度随时间由小变大再变小；综合反映区域地震活动水平的参数RTL面积分——I_RTL从2013年8月开始上升，达到峰值点后回落，峰值点至地震发生的时间间隔为9个月。研究时段近15a时，研究区内发生了2007年宁洱M_S6.4地震，结果表明：宁洱地震前检测到地震活动平静；景谷地震前，先检测到地震活动平静，后于震前1a检测到地震活动增强，异常分布在22.5°~25°N，99.5°~101.5°E范围内，I_RTL峰值与地震发生的时间间隔为7个月。这说明即使发震位置相距较近且震级相当的地震，震前的地震活动变化也会明显不同。对于景谷M_S6.6，不同研究时段检测到的结果虽有不同，但震前地震活动增强异常区的分布和参数I_RTL出现峰值的时间较一致，所以探索RTL空间分布和参数I_RTL与发震位置和时间的关系有重要的研究意义。

关键词: Region-Time-Length(RTL)算法, RTL面积分, 景谷地震, 地震危险性分析

CLC Number:

P315.2

LIU Yue, SHAO Zhi-gang. ANALYSIS OF SEISMICITY CHANGES PRIOR TO THE 2014 YUNNAN JINGGU M_S6.6 EARTHQUAKE[J]. SEISMOLOGY AND GEOLOGY, 2016, 38(4): 1070-1081.

刘月, 邵志刚. 2014年云南景谷M_S6.6地震前地震活动变化分析[J]. 地震地质, 2016, 38(4): 1070-1081.

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