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宁夏地区地震视应力时空变化特征分析

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选取2010年以来宁夏及邻区300余次ML≥2.5地震,计算这些地震的视应力值和相关震源参数,扣除震级对视应力的影响后,得到宁夏四个不同区域的地震视应力结果,并分析该区域视应力与地震活动水平的相关关系.结果表明:(1)宁夏与内蒙古交界地区和香山至天景山地区视应力整体偏低,地震前后视应力无显著异常,分析其原因可能与该区域地震活动水平整体偏低有关;(2)吴忠至灵武地区ML2.5~2.9震级档视应力在2016-2020年期间出现上升-下降异常,该异常可能与2021年灵武ML3.6震群和ML4.5地震有关;(3)海原至六盘山地区ML≥2.5地震视应力在2015-2020年期间出现上升-下降异常,差视应力在2016-2017年期间出现高值异常,该异常可能与2017年固原ML4.9地震有关;(4)宁夏地区视应力高值异常在空间上整体呈北东向分布,与青藏块体东北缘北东向挤压方向一致,表现出相邻区域地震活动水平交替活跃现象,即海原至六盘山地区地震活动水平偏高,相邻的香山至天景山地区地震活动水平偏低,吴忠至灵武地区地震活动水平偏高,相邻的宁夏与内蒙古交界地区地震活动水平偏低;(5)通过研究地震视应力与地震活动的相关关系,可以进一步了解宁夏地区地震活动特点和区域应力状态.
Temporal and spatial variation characteristics of seismic apparent stress in the Ningxia region
In this paper,over 300 earthquakes with ML≥2.5 that occurred in Ningxia and its adja-cent regions since 2010 were selected.The apparent stress values and relevant seismic source pa-rameters for these earthquakes were calculated.After accounting for the influence of magnitude,the seismic apparent stress values for four distinct regions of Ningxia were obtained,and the correlation between apparent stress and seismic activity level was analyzed.Results show the following:(1)The border area between Ningxia and Inner Mongolia,as well as the area from Xiangshan to Tianjingshan,generally exhibit relatively low apparent stress.Notably,no considerable variations in apparent stress are observed before or after notable earthquakes.This phenomenon can possibly be attribu-ted to the generally low level of seismic activity in these regions.(2)During 2016-2020,the apparent stress of ML2.5-2.9 earthquakes in the Wuzhong-Lingwu area demonstrates an anom-alous increasing-decreasing pattern,which may be related to the Lingwu ML3.6 earthquake swarm and ML4.5 earthquake in 2021.(3)The apparent stress of ML≥ 2.5 earthquakes from Haiyuan to Liupan Mountains exhibit an anomalous increasing-decreasing trend from 2015 to 2020,and the differential apparent stress shows a high-value anomaly from 2016 to 2017,which may be related to the Guyuan ML4.9 earthquake in 2017.(4)The anomalously high apparent stress values in Ningxia are mainly distributed in the north-east direction,which aligns with the northeastward extrusion direction of the northeastern margin of the Qinghai-Xizang block,reflecting alternating levels of seismic activity in adjacent regions:the seismic activity level from Haiyuan to Liupan Mountains is high,while that in the adjacent Xiangshan-Tianjingshan area is low;the level of seismic activity in Wuzhong-Lingwu area is high,while that in the adjacent border area between Ningxia and Inner Mongolia is low.The characteristics of seismic activity and regional stress state in the Ningxia area can be effectively understood by studying the correla-tion between seismic apparent stress and seismic activity.

apparent stressseismic activity levelNingxia and its adjacent regions

罗恒之、曾宪伟、李文君、罗国富

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宁夏回族自治区地震局,宁夏银川 750001

视应力 地震活动水平 宁夏及邻区

2025

地震工程学报
中国地震局兰州地震研究所,中国地震学会,清华大学,中国土木工程学会

地震工程学报

北大核心
影响因子:1.191
ISSN:1000-0844
年,卷(期):2025.47(1)