青海玉树活动断裂带的多期古地震滑坡及其年龄  

The characteristics of palaeo-earthquake landslides along Yushu faulted zone and their ages

作　　者：蒋瑶[1,2] 吴中海[2] 刘艳辉[1,2] 田婷婷[1,2] 张铎[2,3] 黄小龙[2] 黄小巾 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质科学院地质力学研究所,北京100081 [3]首都师范大学资源环境与旅游学院,北京100048

出　　处：《地质通报》2014年第4期503-516,共14页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212011120163);中国地质科学院地质力学研究所基本科研业务费项目(编号:DZLXJK201202);国家自然科学基金项目(批准号:41171009)

摘　　要：2010年青海玉树Ms 7.1级地震发生后,笔者在开展玉树灾区地震地质灾害调查中发现13处古地震滑坡遗迹。调查结果表明,玉树古地震滑坡主要集中分布在玉树活动断层两侧5km范围内,规模普遍较大,多具有多期活动特征,且与周围古地震相伴生,空间上体现出发震断层对其发育的控制作用。同时,古地震滑坡地形地貌、沉积特征、年代学特征等方面的证据表明,其常具有原地复发的特征。据古地震滑坡堆积体的AMS14C测年结果,认为目前发现的典型古地震滑坡主要发生在全新世中晚期,并集中分布在5个时期,与古地震探槽揭示的古地震事件期次及发生年代具有较好的对应关系。进一步对比古滑坡规模和分布范围,发现玉树断裂带在全新世中晚期发生2次规模较大的古地震滑坡事件,与地震探槽揭示的古地震特点相符。研究结果表明,群发性古地震滑坡是识别古地震事件的重要地貌标志,可从年代学上揭示古地震事件发生的具体时间,对于补充古地震事件资料和恢复古地震在时间与强度上的分布都具有重要意义。After Yushu Ms7.1 earthquake in 2010, the authors first discovered 13 palaeo-earthquake landslides based on field geologi- cal survey. Studies show that the large-size palaeo-earthquake landslides are mainly distributed along with active faults within 5km on both sides accompanied by the surrounding palaeo-earthquake phenomenon, obviously controlled by Yushu active fault. An analysis of the characteristics of landslide surface morphology, scale and formation age as well as the superimposition relationship between an- cient landslides and the surrounding strata shows that palaeo-earthquakes are characterized by large quantities, in-situ recurrence and multiperiodic activities. The authors further collected ＇4C dating samples from the main scarp of several typical palaeo-earthquake land- slides, and AIMS 14C dating results indicate that they were mainly formed in the middle-late Holocene and focused on five periods, con- sistent well with periods ofpaleoseismic events revealed by digging trenches. A comparison with the sizes ofaU palaeo-earthquake land- slides further implies that the two largest paleo-earthquakes along Yushu faulted zone occurred in Mid-late Holocene The study also demonstrates that the relatively uniform age of massive palaeo-earthquake landslides might indicate the formation time ofpaleoseismicevents, which is of important significance for the recovery and intensity study ofpaleo-seismic events.

关 键 词：青藏高原 地震滑坡 古地震事件 玉树断裂带 地震地质灾害 

分 类 号：P534.632[天文地球—第四纪地质学] P315.9[天文地球—古生物学与地层学]