沂沭断裂带及其附近地区构造应力场研究概要

Study on Tectonic Stress Field in Yishu Fault Zone and Its Adjacent Areas

摘要:

查阅了前人关于沂沭断裂带及其附近地区的构造应力场研究，系统地归纳并分析了这一地区构造应力场演化特征。结果显示，伴随着沂沭断裂带活动习性在不同时期的差异，沂沭断裂带及其附近地区古构造应力场的主应力轴方向在不同时期变化较大，构造应力值在区域内为100 MPa左右；现代构造应力场主应力轴方向基本一致，为NEE向，构造应力值随深度增加，近地表在3 MPa 左右，深部可达几十至100 MPa数量级。但无论主应力轴方向或者构造应力值大小，在局部区域均有一定的复杂性。

Abstract:

Yishu fault zone is the most famous fault zone in eastern China. According to the historical earthquake catalog，the MS8.5 Tancheng earthquake occurred in 1668 along one of the zone's faults known as Changyi-Dadian Fault.Because this fault zone is important in the research of geologic history in addition to that of potential earthquake risk，it is well known by geologists and seismologists. Numerous research papers have focused on the tectonic stress field evolution and characteristics of modern tectonic stress fields in the region near Yishu Fault.Regarding the evolution of the tectonic stress field in the region near Yishu Fault, such research has always included information on geodynamics，tectonic deformation，and structural geometry.However，such research is used to determine the characteristics of tectonic stress fields in multiple periods and is generally based on simulation tests and numerical simulation.All of this research is aimed to reveal the tectonic structural framework as well as tectonic evolution to provide an understanding of the inherited and newly created features of tectonics and，in particular，to provide a basis for study of modern tectonic stress fields. In the region near Yishu Fault，modern tectonic stress field studies have generally focused on crustal movement，focal mechanism solutions，borehole strain measurements，and numerical simulation.Because such research also focuses on the characteristics of spatial distribution and the changes of modern tectonic stress fields，it serves as references for analysis of seismic hazard in this region.In this paper，by analyzing numerous studies，we systematically summarize the characteristics of tectonic stress field evolution for the region near Yishu fault zone.Although there are many different theories on the generation of the Tan-Lu fault zone its active features，we conclude that Yishu fault zone originated through large scale left translation in the early years and the later experienced complex tectonic evolution. Finally, determine that the direction of principal stress axes of the ancient tectonic stress field changed significantly along with the active behavior of this fault zone to reach 100 MPa. With developments in technology，current studies of tectonic stress fields are more encouraging，and many new research methods and novel concepts have been explored. In particular, the development of digital computer simulation techniques has allowed for an increasing number of studies in this research field，such as the progression of stress field numerical simulation from two dimensional to three dimensional and research perspectives from single to multiple levels. On the basis of previous research in the region of Yishu Fault, we conclude that the direction of principal stress axes was consistent with NEE and that principal stress values were increasing with depth from 3 MPa near the Earth’s surface to 100 MPa to approximately at 10 km. These parameters are characterized by complexity regardless of the direction of principal axis or tectonic stress values，particularly near Earth’s surface.Thus，research on the tectonic stress field in the region near Yishu Fault is thorough. Although some of these theories are divers，many viewpoints are still highly significant and provide a basis for further research in estimating potential earthquake risk in this fault zone.