利用宽频带数字地震记录资料，通过对汶川地震、玉树地震、青川地震等震例的反复对比研究，初步识别出可能存在的临震微波动。其特征表现为：①频谱范围较宽，优势频率集中在11～16Hz，频谱形态较为整齐；②在震前12～14天出现，有可能被震中距50km范围内的台站记录到；③可能具有方向性，其活动度变化显著的方位与发震断层、余震分布及震源位置较为一致。临震微波动可能与临震阶段震源区的预活动、微震动、微破裂或临震阶段相关活动构造微活动、微破裂、裂隙扩展等事件有关。

Based on the digital broad-band seismic records,the microwave fluctuation impending earthquake was identified preliminarily through the repeated comparative study of Wenchuan,Yushu,Qingchuan and other earthquakes. Its characteristics are as follows:(1)Dominant frequency of spectrum focuses on 11-16Hz. The spectrum range is relatively wide and its morphology is comparatively neat.(2)The phenomenon observed 12-14 days before the earthquake may be recorded by a station with the epicenter distance within 50km.(3)Directional feature is found,and the direction of significant changes in activity is consistent with the causative fault,aftershock distribution,and source locations. The phenomenon of microwave fluctuation impending earthquake can be related to events such as pre-slip,micro-vibration,micro-fracturing in source areas or some related tectonic activities such as micro-activities,micro-cracks,propagations of cracks during the imminent phase.

P315

“十二·五”国家科技支撑计划专题“数字地震技术在强震中短期预测中的应用”（2012BAK19B02-01）资助