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为了了解区域现今应力状态及其与断层群体之间的关系,我们用两组不同的数据(岩土工程的现场应力数据和地震震源机制解)来描述朝鲜半岛东南部地区的现今应力张量特征。两组数据都给出了相似的结果,即主压应力方向为NEE-SWW向,这与亚欧板块东部一级构造应力分区的构造主应力方向是一致的。经过对现场应力数据以及震源机制反演的更多严格分析可知,现今应力场在方向和大小上呈现出有规律的不均匀性,而这种不均匀性可能是由于断层组的影响引起的。在地壳浅部开展现场应力测量时,一般最大最小水平主应力随空间位置变化,且与垂直主应力正交。研究显示现场应力量值与区域断层逆相关。这表明由于断层活动而产生的应力释放可能是导致区域内低应力区的主要因素之一。为了证实这一推论,我们根据现今应力场仔细调查了新近活动过的第四纪断层的产状。在这一给定的应力条件下,断层滑移面上剪应力与主应力的高比值表明大部分断层位于优势滑移方向,这意味着可能是断层在维持着现在的应力场。当代的地震分布显示低应力区地震活动性密度较大,表明相应区域内的断层强度可能受现今应力状态影响处于摩擦极限状态。这也许告诉我们断层强度的不均匀性导致了区域应力状态的不均匀性。
To understand the current state of stress in the region and its relationship to faulting populations, we describe two different sets of data (geotechnical field stress data and seismic focal mechanism solutions) to describe the current stress tensor characteristics in the southeastern part of the Korean peninsula . Both sets of data give similar results, that is, the direction of principal compressive stress is NEE-SWW direction, which is consistent with the principal tectonic stress direction of the tectonic stress zone in the eastern Eurasian plate. After more rigorous analysis of on-site stress data and inversion of focal mechanism, the current stress field shows regular inhomogeneity in direction and magnitude, which may be caused by the influence of fault groups. When conducting on-site stress measurement in the shallow crust of the crust, the general maximum and minimum horizontal principal stress change with the space position and are orthogonal to the vertical principal stress. Research shows that the magnitude of field stress is inversely related to regional faults. This indicates that the stress release due to fault activity may be one of the main factors leading to the low-stress zone in the area. To confirm this corollary, we carefully examined the occurrence of Quaternary faults that have recently been active, based on present-day stress fields. Under this given stress condition, the high ratio of shear stress to principal stress on the fault slip plane indicates that most of the faults are in the dominant slip direction, which means that it is possible that the fault is maintaining the present stress field. The present earthquake distribution shows that the seismicity density in the low-stress area is large, indicating that the fault strength in the corresponding area may be affected by the present stress state and is in the frictional limit state. This may tell us that the inhomogeneity of the fault strength leads to the non-uniformity of the regional stress state.