日本3·11大地震对郯庐断裂带(中南段)位移场影响的数值模拟研究

THE RESEARCH ON THE IMPACT OF DISPLACEMENT FIELD OF JAPAN 3·11 EARTHQUAKE ON THE SOUTH CENTRAL SECTION OF TANLU FAULT ZONE

通过建立的2个有限元模型,从位移场的角度探究了日本3·11大地震对郯庐断裂带(中南段)区域的影响。结果表明,日本3·11大地震所引起的同震水平位移在郯庐断裂带附近达到了mm至cm级。在郯庐断裂带的东侧,位移值最大处的中国东北地区达到了30mm,在华北地区,位移值最大处的烟台、威海等地也达到了12mm;在郯庐断裂带的西侧,位移值最大的东北地区有20mm,而在华北地区,位移值最大只有8mm。可见郯庐断裂带的东西两侧位移值差别非常明显。总体而言,日本3·11大地震对中国影响比较大的地方主要在郯庐断裂带的北段,即中国东北地区。考虑到实际地壳介质对应变传递的延迟效应,日本3·11大地震对中国郯庐断裂带的实际影响会有1个滞后,因此,2011年以来辽宁、吉林的多次地震与日本3·11大地震可能存在一定的相关性,可见日本大地震对山东、江苏段的影响仍然不可忽视。

Based on the finite element models, in this paper, the impact of Japan 3· 11 earthquake on the south-central section of Tanlu Fault zone is discussed in the view of displacement field. From the displacement magnitude acquired by the numerical simulation of Japan 3· 11 earthquake, this earthquake has a certain impact on Tanlu Fault zone in China's Mainland area. The simulation results show that the coseismic horizontal displacement near the Tanlu Fault zone caused by Japan 3·11 earthquake has reached millimeter to centimeter level. On the east side of the fault zone, the maximum displacement value in Northeast China reaches to 30 millimeters, and the maximum displacement value in Yantai, Weihai and other places of North China also reaches to 12 millimeters. On the west side of the fault zone, the maximum displacement value in Northeast China reaches to 20 millimeters, and the maximum displacement value in North China is only 8 millimeters. The displacement value difference is very obvious in both sides of Tanlu Fault zone. In addition, the simulation results also show that the displacement values in the east-west direction is much bigger than the one in the south-north direction of the Tanlu Fault zone and nearby areas; especially the displacement direction is basically near to east-west direction in North China. Meanwhile, bigger NS- direction displacement appeared in Northeast China, reaches to 8 millimeters. Therefore, the impact of and the maximum displacement value even Japan 3-11 earthquake on this area is more complex. Considering the actual delay effect of crustal medium to stress transfer, the impact of Japan 3·11 earthquake on the Tanlu Fault zone will have a delay, so the follow-up effect will stay for a certain time. Although the displacement value in eastern North China（Tanlu Fault zone and its nearby area） is smaller than the one in Northeast China, the impact of Japan 3· 11 earthquake still cannot be ignored. Considering that many magnitude 4 or 5 earthquakes have occurred in Kenli, Changdao, Rongcheng, Laizhou in Shandong Province and in the Rudong, Gaoyou in Jiangsu Province since 2011, it cannot be excluded the possibility that a larger earthquake will happen in this area in the future. Thus, due attention has to be paid to this.