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作 者:陈江贻 汤兰荣 邓辉 许志山 严宁欣 万祺薇 万康 CHEN Jiangyi;TANG Lanrong;DENG Hui;XU Zhishan;YAN Ningxin;WAN Qiwei;WAN Kang(Jiangxi Earthquake Agency,Nanchang 330026,China)
机构地区:[1]江西省地震局,南昌330026
出 处:《地震地磁观测与研究》2024年第6期21-27,共7页Seismological and Geomagnetic Observation and Research
基 金:中国地震局监测、预报、科研三结合课题(项目编号:3JH-202401049);江西省防震减灾与工程地质灾害探测工程研究中心、江西九江杨子块体东部地球动力学野外科学观测研究站开放基金(项目编号:OGYB202204)。
摘 要:选取2009—2022年江西萍乡及邻区181个M_(L)≥1.8中小地震数字波形资料,基于Brune圆盘模型,结合遗传算法,计算该区地震视应力,通过分析视应力时空变化特征,探讨研究区应力水平。计算结果表明:萍乡及邻区地震视应力值分布在0.0018 MPa—1.76 MPa,平均视应力为0.076 MPa,可作为该区背景视应力水平;视应力值随震级增加而升高,二者整体呈正相关性;视应力的时间变化特征揭示,萍乡及邻区目前处于应力缓慢累积阶段,且整体水平相对较低;视应力空间分布特征表明,较高视应力值集中分布在萍乡—丰城断裂带以北区域。通过震级—频度拟合,得到研究区b值平均约为1.15。分析发现,研究区中小地震密集区域集中在萍乡—丰城断裂带上的低b值异常区,而此区域视应力值也相对较高,表明低b值、高视应力值区域与中小地震密集区分布较为吻合。进一步分析可知,研究区地震活动强度和视应力水平均低于江西省其他地区,但小震活动频繁,可能与该区煤矿资源的广泛分布以及可溶性岩层较为发育有关。The digital waveform data of 181 small and medium earthquakes M_(L)≥1.8 in Pingxiang and adjacent areas of Jiangxi Province from 2009 to 2022 were selected.Based on Brune disk model and genetic algorithm,the apparent seismic stress in the area was calculated.By analyzing the spatio-temporal variation of the apparent stress,the stress level in the study area was discussed.The results show that the apparent stress values in Pingxiang and its adjacent areas range from 0.0018 MPa to 1.76 MPa,and the average apparent stress is 0.076 MPa,which can be used as the background apparent stress level in this area.The apparent stress value increases with the increase of earthquake magnitude,and they are positively correlated with each other.The temporal variation of the apparent stress reveals that Pingxiang and its neighboring areas are in the stage of slow accumulation of stress,and the overall level is relatively low.The spatial distribution characteristics of the apparent stress show that the higher apparent stress values are concentrated in the north of the Pingxiang-Fengcheng fault zone.Through magnitude-frequency fitting,the average b-value in the study area is about 1.15.It is found that the small and medium earthquake intensive area is concentrated in the low b-value anomaly area of this fault zone,and the apparent stress value of this area is relatively high,indicating that the distribution of low b-value and high apparent stress value is more consistent with the distribution of small and medium earthquake intensive area.Further analysis shows that the seismic activity intensity and apparent stress level in the study area are lower than those in other areas of Jiangxi Province,but the frequent small earthquakes may be related to the wide distribution of coal resources and the relatively developed soluble rock formation in the area.
关 键 词:萍乡及邻区 震源动力学参数 视应力 时空变化特征 B值
分 类 号:P31[天文地球—固体地球物理学]
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