论文部分内容阅读
以中国东北部地区的GPS观测资料为基础,研究了2011年3月11日日本东部MW9.0大地震对中国东北部地区的地壳形变场状态、活动构造的运动方式及地震危险性态势的影响。结果表明,该地震所引起的同震地壳应变场与研究区域长期地壳应变率场相对比,两者在主应变方向和大小等方面,整体上并无明显的一致性。该地震主要影响了中国东北区域应变积累水平,同震位移在瞬间所产生的应变,相当于该区域约12.7a的长期积累。而在东北以外的其他区域,同震应变对背景应变场的影响并不明显。基于同震应变以及背景应变场,选取了4个重要的活动断裂区段,利用一系列跨断裂连续GPS基线端点相对位置的时间变化序列进行分析,发现该地震使郯庐断裂北段发生了明显的左旋错动和拉张运动,且震后的变化趋势反映着轻微的继续左旋和拉张;而对于郯庐断裂的中段,该地震并没有产生明显的错动和拉张,仅使其震后的右旋运动速率有轻微的加快;对于华北地区的张家口-蓬莱断裂带,虽然在地震后约1a时期内表现为右旋挤压运动,但随后则快速回归到原有的左旋拉张运动,反映出这次地震的发生使该断裂的应力积累首先得到短暂的释放,随后区域应力又回归到原有水平;太行山山前断裂带的运动态势未受这次地震的显著影响,因而推断出此次地震的影响范围并未波及到山西地堑系。总体而言,3·11日本大地震的发生,使中国东北部区域的地壳应变积累和应力水平有所缓解,因此,在某种程度上缓解了区域的地震危险性。
Based on the GPS observations in the northeastern part of China, the crustal deformation field, the moving tectonic mode of movement and the earthquake hazard situation in the northeastern part of China were studied on the March 11, 2011, east Japan MW9.0 earthquake . The results show that compared with the long-term crustal strain rate field caused by the earthquake, both the coseismic crustal strain field and the long-term crustal strain rate field caused by the earthquake have no obvious consistency in terms of the main strain direction and size. The earthquake mainly affected the level of strain accumulation in the northeastern China, and the coseismic displacement generated in an instant, corresponding to a long-term accumulation of about 12.7 years in this area. In other areas beyond the northeast, the effect of coseismic strain on the background strain field is not obvious. Based on the coseismic strain and the background strain field, four important active fault sections were selected and analyzed using a series of time series of the relative positions of successive GPS baseline endpoints across the fault. It was found that the earthquake caused obvious obvious changes in the northern part of the Tanlu fault , And the trend of post-earthquake changes reflects a slight continuation of left-lateral and extension. For the middle section of the Tan-Lu fault, the earthquake did not produce obvious dislocation and tension, and only enabled the earthquake The right-lateral movement rate slightly accelerates. For the Zhangjiakou-Penglai fault zone in North China, although it is characterized by a right-handed squeeze movement in the first lapse after the earthquake, it quickly returns to the original left-lateral tension movement , Reflecting the occurrence of this earthquake so that the stress accumulation of the fault was firstly released briefly and then the regional stress returned to its original level. The movement of the Taihangshan piedmont fault zone was not significantly affected by the earthquake, and it was deduced The scope of this earthquake did not affect the Shanxi Graben. Overall, the 3.11 Japan earthquake eased the accumulation of crustal strain and stress levels in the northeastern region of China, and therefore, to a certain extent, mitigated the earthquake risk in the region.