巴塘断裂黄草坪段地震地裂缝破裂特征及成因机理研究  

RESEARCH ON RUPTURE CHARACTERISTICS AND GENESIS MECHANISM OF SEISMIC GROUND FISSURE IN HUANGCAOPING SECTION OF BATANG FAULT

作　　者：黄伟亮 项闻 李宇 王世元[2] 杨虔灏 刘妮娜 HUANG Weiliang;XIANG Wen;LI Yu;WANG Shiyuan;YANG Qianhao;LIU Nina(College of Geological Engineering and Surveying of Chang an University,Key Laboratory of Western China Mineral Resources and Geological Engineering,Xi'an 710054,China;Earthquake Administration of Sichuan Province,Chengdu 610041,China)

机构地区：[1]长安大学地质工程与测绘学院,西部矿产资源与地质工程教育部重点实验室,中国西安710054 [2]四川省地震局,中国成都610041

出　　处：《工程地质学报》2023年第5期1655-1667,共13页Journal of Engineering Geology

基　　金：国家自然基金(资助号:42041006,42277152);长安大学中央高校基本科研业务费专项资金(资助号:300102262910).

摘　　要：地裂缝是地表岩土体内产生线性破裂的一种地质灾害,其中构造型地裂缝形成和发展与活动断层的运动特征密切相关。现有构造型地裂缝的报道大多与断层蠕滑活动有关,而针对断层黏滑运动(地震)所形成的地裂缝通常统一划分为地震地表破裂带,主要注重对其分布特征的调查,而针对其中单条地裂缝破裂特征和成因机理研究较为少见。本文以巴塘断裂在黄草坪段所形成的地裂缝为研究对象,通过野外地质调查、无人机测绘、野外槽探、物探等手段,揭示了地裂缝的浅-中-深几何结构及其成因机理。巴塘断裂在黄草坪段形成一槽谷地貌,地裂缝在槽谷中表现为一条具有线性特征的地貌陡坎S_(1),坎高为0.26±0.03m。横跨槽谷的探槽揭露出陡坎下部及两侧密集发育有18条地裂缝,根据地裂缝贯通上覆地层的情况可大致划分出3个活动时期,可能代表巴塘断裂全新世以来的3次地震事件,部分地裂缝贯通至地表与S_(1)陡坎相连,这可能是1870年巴塘M 7^(1)/_(2)地震所致。横跨槽谷的地震反射剖面中表现出槽谷边界受控于两条相向而倾的铲型断裂,两条断裂共同形成了“Y”字型拉张地堑结构,而在地堑内部表现出有近直立的反射层变形带,位置大致可与陡坎S_(1)对应。全新世以来,巴塘断裂在右旋走滑过程中,在局部近地表形成多级“Y”字型拉张地堑构造,而地堑内部地裂缝密集发育,且地裂缝形成及贯通上覆土层过程与巴塘断裂地震活动密切相关,因此该地裂缝形态受巴塘断裂几何结构控制,活动期次与巴塘断裂的强震活动相对应,具有典型地震地裂缝的特点。Ground fissure is a kind of geological disaster and caused by linear fracture in surface rock and soil.The formation and development of tectonic ground fissures are closely related to the movement characteristics of active faults.The existing reports of tectonic ground fissures are mostly related to fault creep-slip movement,but the ground fissures formed by fault stick-slip(earthquake)are generally divided into seismic surface rupture zones.The main focus is on the investigation of their distribution characteristics.Research on the rupture characteristics and genetic mechanism of a single ground fissure is rare.In this paper,the ground fissure formed in Huangcaoping section of Batang fault is taken as the research object.The shallow-medium-deep geometric structure of ground fissures and their formation mechanisms have been revealed through field geological surveys,unmanned aerial vehicle surveying and mapping,field trenching,and geophysical prospecting.Batang fault forms a valley landform in Huangcaoping segment.The ground fissure in the valley shows a linear geomorphic scarp S_(1)with a height of 0.26±0.03m.The geological trench across the valley revealed 18 ground fissures densely developed under and on both sides of the steep slope.Based on the situation of ground fissures penetrating into the overlying strata,three active periods can be roughly divided,which may represent three seismic events since the Holocene on Batang Fault.Part of the ground fissure penetrated to the surface and connected with scarp S_(1),which may be caused by Batang M 7^(1)/_(2) earthquake in 1870.The seismic reflection profile across the valley shows that the valley boundary is controlled by two listric faults which dip towards each other.The two faults together form a“Y”shaped tensile graben structure.In the graben,there is a near-vertical deformation zone of reflection layer,which roughly corresponds to the S_(1).Since the Holocene,during the right-lateral strike-slip process of the Batang fault,a multi-level“Y”-shaped exte

关 键 词：地裂缝 巴塘断裂 古地震 浅层地震反射剖面 1870年巴塘地震 

分 类 号：P642.27[天文地球—工程地质学]