大地震震前热异常提取方法的对比研究——以2014年M_(W)6.9于田地震为例  

COMPARATIVE STUDY ON THERMAL ANOMALIES DETECTION METHOD BEFORE STRONG EARTHQUAKE:TAKING THE 2014 M_(W)6.9 YUTIAN EARTHQUAKE AS AN EXAMPLE

作　　者：吴玮莹 单新建[1] 屈春燕[1] 李新艳[2] WU Wei-ying;SHAN Xin-jian;QU Chun-yan;LI Xin-yan(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Earthquake Agency of Ningxia Hui Autonomous Region,Yinchuan 750001,China)

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [2]宁夏回族自治区地震局,银川750001

出　　处：《地震地质》2022年第6期1503-1520,共18页Seismology and Geology

基　　金：国家重点研发计划项目(2018YFC1503602)资助。

摘　　要：地震震前热参数异常提取方法的可靠性对于地震震前热参数异常变化研究至关重要。文中以2014年2月12日于田M_(W)6.9地震为典型震例,以2008年汶川M_(W)7.9地震为验证震例,对目前研究中广泛使用的2种异常提取方法:ZS(Z-score)法和RST(Robust satellite technology)法在实际震例中的提取效果、对异常变化的敏感程度、对背景信息的抑制能力和对地震信息的指示性4个方面进行了详细的定性和定量化评估。于田地震震前,地表温度和长波辐射出现了多次间歇性突发异常,随着地震的邻近,异常出现的频次增加,异常空间分布逐渐向断裂带周围集中,最大异常变化出现在地震前一个月。2种方法提取结果的差异主要表现在异常变化出现的频率和幅度上,RST法得到的异常频次和幅度都高于ZS法。为探究造成差异的原因,我们进一步结合地震前后2个地震平静年的数据,对2种方法进行了定量化评估,结果表明:(1)ZS法和RST法对于微弱异常变化都具有一定的敏感性;(2)ZS法相较于RST法对于其他因素引起的热参数异常变化的抑制作用更强;(3)针对地表温度数据,ZS法的提取结果对地震震中的指示性略优于RST法,而RST法对于长波辐射数据的效果则更好;ZS法的归一化距离指数最大值出现的时段距离发震时段更近;(4)汶川地震的定量化对比结果与于田地震略有不同,这可能是受到研究区地物类型分布的影响。综合上述研究成果,我们认为ZS法是更为简便有效的地震热参数异常提取方法。针对震前热参数异常提取方法的对比研究有助于我们了解不同方法的优缺点和适用性,提高地震热参数异常提取的可靠性。The reliability of anomaly extracting methods is crucial for pre-seismic thermal anomalie research.However,there is a lack of relevant researches.We compared two commonly used anomal extracting methods,Z-score(ZS)and Robust satellite technology(RST)method,taking the 2014Yutian earthquake as a typical example and the 2008 Wenchuan earthquake as a validation.The fou aspects of extracted results are compared qualitatively and quantitatively,including the extraction effect,sensitivity to slight change,suppression of background information and indication of seismi information in the actual earthquake case.Moreover,the extracted results of validation case are used to validate the reliability of typical case results.Many intermittent anomalies in surface temperatur and outgoing longwave radiation appeared before Yutian earthquake.The frequency of anomalie increases with the proximity of earthquake.The spatial distribution of surface temperature and outgoin longwave radiation anomalies gradually concentrated around the fault zone at the same time.Th largest surface temperature and outgoing longwave radiation anomalies occurred one month befor Yutian earthquake.The difference between the extraction results of ZS and RST method is mainl manifested in the frequency and amplitude of anomaly changes.The frequency and amplitude o anomaly changes obtained by RST method are higher than those obtained by ZS method.To furthe explore the reason for these differences,we further evaluate the two methods quantitatively b combining the data of two non-seismic years before and after Yutian earthquake respectively.Th sensitivity of anomaly extraction method represents its ability to identify the slight changes of therma parameters caused by the seismogenic process.The two methods are sensitive to slight changes,bu the RST method is better than ZS method.The background information represents normal variation in surface temperature and outgoing longwave radiation caused by non-seismic factors.Suppression o background information determines

关 键 词：于田M_(W)6.9地震 震前热异常 ZS法 RST法 定性与定量对比 

分 类 号：P314.3[天文地球—固体地球物理学] P315.72[天文地球—地球物理学]