摘要
华北地区是典型的板内地震带,其地震时空活动特征及断裂带之间的力学耦合关系备受关注并得到广泛研究.前人研究主要基于天然地震目录,但由于其存在记录时间短且震级不完备的问题,可能会导致我们对地震活动特征及规律认识不足.为此,本文通过构建华北地区复杂断层系统的三维黏弹塑性岩石圈动力学有限元模型,模拟了区域的背景应力场、速度场及断层系统上的地震时空活动,获得了研究区数万年的长期合成地震目录,调查了研究区地震矩释放率的时空特征,探讨了区域断裂带之间的相互力学耦合作用.模拟结果和观测数据在区域应力场、地表变形、地震b值及断层滑动速率等方面均具有较好的一致性.基于合成地震目录的统计分析表明,与华北地区东部的断裂带相比,其西部的汾渭断裂带与河套断裂带上的地震活动性更高.此外,汾渭断裂带与华北平原内部断裂带的地震矩释放率随时间的演化过程中,有时表现出相互抑制、此消彼长的关系,有时也展现出趋势相同、同消同长的特征.本研究可以帮助克服观测的地震目录数据存在的一些问题,对认识华北地区的地震活动时空特征及断层带之间的相互力学耦合作用具有重要意义.
The North China region is a typical intraplate seismic zone,and its spatiotemporal characteristics of seismicity and the mechanical coupling among fault zones have been extensively studied.Previous studies mainly focused on natural seismic catalogs.This tended to cause insufficient understanding of characteristics and rules of regional seismicity due to these short-term and incomplete seismic catalog data.This study builds a three-dimensional viscoelastoplastic finite element model with the complex fault system in the North China,simulates the background stress field,crustal motion velocity field,fault slip rates,and spatiotemporal seismicity in the fault system,obtains the regional long-term synthetic seismic catalog with timescale of tens of thousands of years,investigates spatiotemporal characteristics of seismic moment release rates,and explores mechanical coupling between fault zones.The model results are consistent with observation data on regional stress field,crustal motion velocity field,b value,and fault slip rates.Statistical analysis from the synthetic seismic catalog shows that the seismicity on the Fenwei and Hetao fault zones around the Ordos block in western North China is higher than that on the fault zones in its east.The relationship of seismic moment release rates on the Fenwei fault zone and the internal fault zones of the North China Plain can be complicated:evolutions of seismic moment release rates on them over time do not only show the complementary interdependence,but also show the interdependence of simultaneous changes,including simultaneous increases or decreases.This study can help to overcome some shortcomings of the naturally observed seismic catalog data,and have great significance for understanding the spatiotemporal characteristics of seismicity in North China and the mechanical interaction between its fault zones.
作者
罗纲
宋建
张琦
陈宇轩
靳锡波
尹力
LUO Gang;SONG Jian;ZHANG Qi;CHEN YuXuan;JIN XiBo;YIN Li(School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China;Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,Wuhan University,Wuhan 430079,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China)
出处
《地球物理学报》
北大核心
2025年第9期3415-3432,共18页
Chinese Journal of Geophysics
基金
国家自然科学基金(41974107)
国家重点研发计划项目(2021YFC3000605,2022YFC3003501)资助.
关键词
地震活动时空特征
断层相互作用
华北地区
黏弹塑性有限元模型
合成地震目录
Spatiotemporal characteristics of seismicity
Fault interaction
North China
Viscoelastoplastic finite element model
Synthetic seismic catalogs
