摘要
断裂带上的地震活动,尤其是现代强震活动,一直是活动构造研究的重要内容。随着研究的深入,研究的对象也从一条断裂带上的强震活动,发展到多条断裂带所构成的空间内的强震活动和断块的强震活动。汶川地震和玉树地震后,巴颜喀喇断块的活动引起了广泛的关注。本文从巴颜喀喇断块整体运动的角度出发,根据断块周边各条断裂带上1900年以来的历史强震记录(Ms≥7)和现代强震活动,分析了断块的地震活动及其准周期性、震源机制、最大震级以及边界走滑断裂与强震活动的关系,主要的认识有:①1900年以来,地震活动呈现出3个地震系列,即:1923～1937年叠溪—花石峡地震系列、1947～1976年达日—炉霍地震系列和1997年开始的昆仑—汶川地震系列;②地震系列之间的时间间隔和每一次地震系列持续时间有较大的差异,达日—炉霍地震系列与前后两次地震系列差别较大,而昆仑—汶川地震系列尚未结束;③经过2次8级和8级以上大地震之后,昆仑—汶川地震系列虽然尚未结束,今后还可能发生较大地震,但是巴颜喀喇断块很可能已经历了本地震系列的大释放阶段,在该地震系列时间范围内大释放阶段之后的地震震级将小于大释放阶段的震级;④走滑断裂是控制巴颜喀喇断块运动的主要边界断裂,走滑型强震是地震系列的主体;⑤印度板块向北存在一个强烈的推挤过程,是使这些边界断裂带从孕震到真正发生强震的重要条件。
Seismic activities,especially modern large earthquakes along fault zones have long been a key issue in research of active tectonic.With increasing study in this field,the research target currently focuses on large earthquakes occurring in both spaces consisting of several faulting zones and faulting blocks rather than in one faulting zone.After the Wenchuan and Yushu earthquakes,activities of the Bayankala faulting block have attracted extensive concern.Based on overall movement of the Bayankala faulting block,and combined with all the historical record of large earthquakes（Ms≥7） occurring in each faulting zone since 1900 and analysis of modern seismic activities,this study analyzed these seismic activities and their quasi-periods,focal mechanism,maximum magnitudes,and the relationship between strike-slip faults in boundaries and large earthquakes.The main understanding in this study is as follows.①There were three earthquake series since 1900：the Diexi-Huashixia earthquake series（1923～1937）,the Dari-Luhuo earthquake series（1947～1976） and the Kunlun-Wenchuan earthquake series（since 1997）.② There are big differences in the time interval of two series and the duration time of each earthquake,a bigger difference occurs in the Dari-Luhuo series and the other two series,and the Kunlun-Wenchuan series is not over yet.③ After the Kunlunshan Ms8.1 earthquake and Wenchuan Ms8.0 earthquake,the Kunlun-Wenchuan series is not over yet and big earthquakes are very likely to happen.Although the Bayankala faulting block has released most energy,within the time scope of earthquake series,the magnitudes of earthquakes after release of a large amount of energy are likely lower than that of earthquakes following release of a small amount of energy.④ Strike-slip faults are the major boundary faults which controlled the movement of Bayankala fault-block,forming the major part of each series.⑤ Strong northward extrusion of Indian plate is the most vital condition for earthquakes from formation to development and finally to occurrence in these boundary faults.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2013年第1期9-19,共11页
Acta Geologica Sinica
基金
国家科技支撑计划项目"汶川地震断裂带科学钻探"资助的成果
关键词
青藏高原
巴颜喀喇断块
走滑断裂
地震系列
Tibetan plateau
Bayankala fault-block
strike-slip fault
earthquake series
