云南地区中强地震前应变释放特征

利用云南区域台网地震目录资料，以地震应变能作为地震释放量度，基于应变释放加速模型对前兆地震序列进行非线性模拟. 结果表明: 云南地区1966—2013年发生的115例M_S≥5.0地震中，具有加速特征的有79例，占69%；具有减速特征的有28例，占24%；数据太少无法判断加减速特征的有8例，占7%. 主震为孤立型的前兆地震序列，其减速或数据少类型所占比例远大于加速型；主震为走滑型的前兆序列，其加速型序列要比主震为正断型或逆冲型序列多15%左右. 搜索半径与前兆序列持续时间呈反比关系. 对前兆地震序列模拟结果表明，主震的预测震级和时间误差为±0.3和0.5年. 

Characteristics of strain release before moderate-strong earthquakes in Yunnan region

Referring to the earthquake catalogues produced by the Yunnan Regional Seismic Network，and setting the seismic strain energy as a scale of the seismic energy release，this paper conducts a nonlinear simulation for the precursory earthquake-sequences based on the accelerating strain release model. In the period from 1966 to 2013，115 earthquakes with M_S≥5.0 occurred in Yunnan region. Among them，79 events are characterized by accelerating strain release，accounting for 69%. And 28 events are featured as decelerating strain release，accounting for 24%. The strain releases of the rest eight events accounting for 7% fail to show the features of acceleration or deceleration due to the less seismic data. As to the precursory earthquake sequences whose main shocks belong to the single-shock type，the ones whose earthquake strain releases are accelerating，or the ones lacking seismic data，are far more than the ones whose strain releases are accelerating. As to the precursory earthquake sequences whose main shocks belong to the strike-slip type，the ones whose earthquake strain releases are accelerating are 15% more than the ones whose main shocks belong to the normal-fault type，or 15% more than the thrust-fault type ones. The searching radius has an inverse relation with the duration of the precursory earthquake sequence. The simulated results for the precursory earthquake-sequences indicate that the error of the main shock’s magnitude is ±0.30，and the error of the main shock’s occurrence time is ±0.5 year.