CAJ | 학술논문

利用首都圈地区小震重新定位结果, 研究了2006年7月4日河北文安5.1级地震前地震活动特征, 结果表明: ① 文安地震前5年, 河北平原带中段M_L≥3.0地震活动出现明显的增强(持续43个月)-平静(持续17个月)特点, 蠕变曲线表现为加速-转平; ② 震前4年, 在15～20 km深处存在一个纬向长约70 km、经向长约90 km的三维空区, 文安地震的起始破裂点位于该三维空区的下部边缘; ③ 2003年4月～2004年10月, 平原带中段M_L≥2.0地震震源深度从10 km的浅处逐渐增加到30 km左右的深处, 在此过程中, 中下地壳(20～30 km深度范围内)地震活动显著增强.
이용수도권지구소진중신정위결과, 연구료2006년7월4일하북문안5.1급지진전지진활동특정, 결과표명: ① 문안지진전5년, 하북평원대중단M_L≥3.0지진활동출현명현적증강(지속43개월)-평정(지속17개월)특점, 연변곡선표현위가속-전평; ② 진전4년, 재15～20 km심처존재일개위향장약70 km、 경향장약90 km적삼유공구, 문안지진적기시파렬점위우해삼유공구적하부변연; ③ 2003년4월～2004년10월, 평원대중단M_L≥2.0지진진원심도종10 km적천처축점증가도30 km좌우적심처, 재차과정중, 중하지각(20～30 km심도범위내)지진활동현저증강.
Characteristics of seismic activity before the July 4, 2006 earthquake of M5.1 in Wen'an, Hebei province were analyzed by relocation of small earthquakes in China's capital area. Some results are obtained as below: ① The seismic activity of M_L≥3.0 in the middle part of the Hebei plain seismic belt displayed a feature of strengthening (lasting 43 months)-quiescence (lasting 17 months ) 5 years before the Wen'an earthquake. Simultaneously, the strain release curve showed a variation process of accelerating-flatting. ② A seismogenic gap in three-dimensional space, located in the depth of 15～20 km, with 70 km long in latitude direction and 90 km long in longitude orientation, was formed by M≥2.0 earthquakes 4 years prior to the Wen'an earthquake. The initial rupture point of the Wen'an earthquake situated at the bottom of the gap. ③ The focal depths of M_L≥2.0 earthquakes in the middle part of the Hebei plain seismic belt gradually deepened from 10 km to 30 km from April, 2003 to October, 2004. Meanwhile the seismic activity obviously strengthened in the middle and lower crust (from 20 km to 30 km in depth).