古地震事件震级或强度大小限定的讨论  

Discussion on the magnitude or intensity limitation of paleoearthquake events

作　　者：高云鹏 刘静[1] 韩龙飞 邵延秀 姚文倩 徐晶[2] 胡贵明 王子君[1] 屈孜屹 徐恩民 GAO Yunpeng;LIU Jing;HAN Longfei;SHAO Yanxiu;YAO Wenqian;XU Jing;HU Guiming;WANG Zijun;QU Ziyi;XU Enmin(School of Earth System Science,Tianjin University,Tianjin 300072,China;The Second Monitoring and Application Center,China Earthquake Administration,Xi’an 710054,Shannxi,China)

机构地区：[1]天津大学地球系统科学学院,天津300072 [2]中国地震局第二监测中心,陕西西安710054

出　　处：《地质力学学报》2023年第5期704-719,共16页Journal of Geomechanics

基　　金：国家重点研发计划项目(2021YFC3000605-04)。

摘　　要：震级是表征地震能量大小的重要参数,但在古地震研究中,由于难以精确给定与地震矩紧密相关的破裂参数,故而无法直接计算事件的震级大小。研究者通常假定事件序列为震级相似的特征地震,或基于震级已知的历史地震地表破裂参数获取经验关系来进行震级估算。但已有研究表明特征地震的假设过于简化,而利用经验关系估算震级的方法也受限于各种误差,因此亟需探索新方法以提升古地震事件震级或规模大小评估的合理性。近年来,三维组合探槽的成功应用表明探槽内蕴含着丰富的事件变形信息,进而证实了在探槽内评估事件规模大小的可行性。基于此,文章以阿尔金断裂铜矿探槽为例,利用探槽揭示的事件变形强度,包括垂向位移量、变形带宽度和裂缝总拉张量,来评估事件序列的规模。数据分析结果表明,事件变形强度参数与震级相对大小具有一定的正相关性,且各参数之间也呈现部分相关性。因此,探槽中事件变形强度信息可以判断事件震级的相对大小,充分挖掘探槽内的事件变形信息可为合理评估古地震事件的震级提供借鉴和参考,在古地震研究中应加以重视。The magnitude is an important parameter that characterizes the size of earthquakes.However,in paleoearthquake studies,it is difficult to precisely determine the rupture parameters closely related to seismic moment,making it challenging to directly calculate the magnitude of events.Researchers often assume that event sequences consist of characteristic earthquakes with similar magnitudes or use empirical relationships based on known magnitudes of historical earthquakes to estimate magnitudes.However,previous studies have shown that the assumption of characteristic earthquakes is overly simplistic,and magnitude estimation based on empirical relationships is limited by various errors.Therefore,there is a pressing need to explore new methods to improve the reliability of magnitude assessments for ancient earthquake events.In recent years,the successful application of three-dimensional combination trenches has demonstrated that these trenches contain rich deformation information about events,confirming the feasibility of assessing event sizes within trenches.Using the example of the Copper Mine trench on the Altyn Tagh fault,this article utilizes the deformation intensity revealed within the trench,including vertical displacement,deformation zone width,and total tensile strain,to estimate the scale of the event sequence.Data analysis results indicate that the deformation intensity parameters have a certain positive correlation with the relative magnitude,and there is also some correlation among these parameters.Therefore,the information on deformation intensity within the trench can be used to assess the relative magnitude of events,and fully exploring the deformation information within trenches can provide valuable insights and references for the reasonable evaluation of the magnitude of paleoearthquake events.This underscores the importance of considering such information in paleoearthquake research.

关 键 词：震级限定 古地震事件 经验关系 变形强度 铜矿探槽 

分 类 号：P65[天文地球—地质学]