【摘要】 华北地区的地震活动格外活跃,其地壳深部构造的独特性决定了其地震活动性。多条地学断面和地震剖面等地球物理研究表明,华北地区的地震带(即活动构造带)一般均存在低速体或上地幔上隆;华北强震区的地球物理详细勘测发现,强震区也都存在低速体或上地幔上隆。应用应力摩尔圆和库伦破裂准则,利用上涌模型和地壳减薄模型研究地壳岩石破裂机制,结果表明,存在上地幔上隆和低速体的地区的地壳岩石比其它地区更易于发生破裂。华北地区的地壳深部构造决定了地震的空间分布格局。更多还原

【Abstract】 Seismicity in North China has been very active.The particularity of deep crustal structure determines the activity of earthquakes there.Studies of many geoscience transects and seismic survey profiles indicated that there bodies of low-velocity media in crust or the top anomalous uplifts of the upper mantle are in the seismic zone(i.e.the active tectonic zone) of North China.Detailed geophysical surveys in strong earthquake districts discovered the bodies of low-velocity media in crust or the top anomalous uplifts of the upper mantle too.Using stress Mohr circle and Coulomb failure criteria,this paper presents uplift model and crust-thinning model to study the crust fracture mechanism in North China.The result indicates that the crust would like to fracture if the uplift of the upper mantle or bodies of low-velocity media in crust exist in this region.更多还原