Study On The Correlation Between The Development Of Ground Fissure And The Intensity Of Earthquake

Fen Wei basin is a famous zone of ground fissure and earthquake activity in China, as the deepening of the ground fissure investigation in recent years, a great deal of substantial research on ground fissure has been completed, such as distribution regularities,active characteristics, formation mechanism and engineering precautions.In recent years, considering the characteristic of the Fen Wei graben system,the correlation between the development of ground fissure and the intensity of earthquake is more and more aroused the interest of the researchers, but there are still many questions need to solve.The earthquake is a intense manifestation of the crustal movement,while ground fissure as a non-seismogenic structure surface is often affected by the internal and external motivation and the impact of human activities significantly,understanding the correlation between them has important theoretical and practical significance for further research on the cause of ground fissure,the disaster prevention and mitigation.The ground fissure and the earthquake in Fen Wei basin as the main research object, this paper studies the correlation between them through the collection of relevant information, documents, data.First of all, in the comprehensive collection and collation of ground fissure in Fen Wei area,based on the survey data as of 2014,the 1:500000 distribution of ground fissure has been drawn,to clarify the development background,distribution characteristics, the nature of ground fissure;Secondly, based on the time of ground fissure and the historical background of our seismic network construction,we focus on collecting ML2.0 earthquake catalog of Fen Wei graben system since 1970, researching the seismic activity of Fen Wei graben system and each faulted basin by the analysis of earthquake catalogue integrity;Finally, based on the evolution and space-time distribution regularity of ground fissure and the earthquake, combined with basement faults,we investigate and analyze the links and correlations between them.The study found that:(1)So far Fen Wei basin has developed 534 ground fissures, concentrated in the 1991-2005 period.Located in the central and southern regions, the fissure density is significantly higher than that of the northern region, which has not yet found one in Xin Ding basin, Wei He basin has the largest number.The vast majority are structural fissures, with mass characteristics, tend to be concentrated in the vicinity of fault. Part of the fissures and the underlying fault are connected or overlapped, having the inherited nature of the fault activity.(2)Since 1970, the seismic activity of Fen Wei basin showed the characteristics of high frequency and low energy, mainly in weak earthquake, small earthquake and earthquake swarm activity, the earthquake swarm activity is very prominent in recent years of seismic events in the area, above 5.0 strong earthquake happened just over a dozen times.The whole is bounded by the Yun Cheng basin, the area north of Yun Cheng Basin has high seismic intensity, above 5.0 earthquake swarm activity had occurred in eastern area of Da Tong basin; Above 2.0 earthquake occurred more than 1600 times in Tai Yuan Basin, which contains 3 above 5.0 earthquake and several small swarms; Above 5.0 earthquake occurred 3 times in Lin Fen basin, the latest time is the 2010 earthquake in He Jin; Seismic intensity is generally low in south of Yun Cheng, Yun Cheng and Wei He basin had only happened one 5.0 earthquake respectively.(3)There are following mainly correlation between the regional development of ground fissure and seismic activity intensity:One is that, the strong earthquake directly or indirectly generate(intensify) structural ground fissure, but the generation(expansion) of ground fissure is related to earthquake magnitude, only above 5.0 can easily induce ground fissure, characterized as consistency between the development of ground fissure and the distribution of strong earthquake, such as ground fissure in Da Tong and Jing Yang; Second, there exists obvious space-time difference between ground fissure and small earthquake activity, which is complementary, such as in Jiao Cheng fault zone and the piedmont of Luo Yunshan,showing that small earthquake and ground fissure of the area are independent each other geological phenomenon,they are two different forms of regional tectonic movement and the release of energy, but also reflects the common unified tectonic stress field.(4)According to the distribution of ground fissure and earthquake, Fen Wei basin can be divided into three sections:North section mainly includes the Da Tong and Xin Ding basin, having the minimum number of ground fissure, the tectonic movement form is mainly strong earthquake activity in recent years; South section mainly includes Wei He and Yun Cheng basin, which seismic activity is relatively low, while having more than half of the total number of ground fissure in Fen Wei basin, the tectonic movement is dominated by ground fissure;The middle section includes Tai Yuan and Lin Fen basin, which ground fissure and earthquake are very developed.Therefore, overall, the distribution pattern of ground fissure and earthquake in Fen Wei basin can be summarized as "earthquake in the north, ground fissure in the south, both in the middle ".