河南内乡-镇平ML4.7级地震及其震前 地震活动特征

2000年4月29日河南内乡－镇平ML4．7级地震是一次显著地震事件，地震序列属孤立型，根据震区地震地质背景，等震线分布以及震源机制解的综合分析表明，发震断层为北西向的朱阳关－桐柏断裂，对1992年至今该区2．0级以上地震空间分布的研究认为，震前的地震空间分在由无序到有序的演化过程，即存在一个地震正常活动，地震空间，地震条带，震前震中区平静至发震的发展过程。

The ML4.7 Neixiang-Zhenping e arthquake and characteristics of seismicity before earthquake

The ML4.7 Neixiang -Zhenping earthquake，Henan province occurred on Apr.29,2000 is a remarkable event, which is solitary type. B ased on the synergetic analysis of the seismogeological background, the distribu tion of isoseismic line and focal mechanism solution, it is considered that the Zhuyangguan-Tongbai fault with NW strike is causative structure. The spatial dis tribution of shocks with ML≥2.0 before this event shows that there is the evolution process from disordred to ordred,such as the normal seismic activity, s eismic gap,seismic belt,seismic quiet before the ML4.7 earthq uake.