【摘要】 在一维单侧有限移动震源模式下, 根据拐角频率的方位变化, 利用最小二乘法研究了1995 年7月20日河北沙城ML4.1地震的发震断层面参数。结果表明, 这次地震的断层面破裂方向为224°, 与余震分布和震源机制的NE向节面一致。地震马赫数v/c约为1.85, 即平均破裂速度大于S波速度, 为一次超速破裂。若取横波速度为3.5 km/s, 则破裂长度约为1 km。因此, 这次地震破裂以超S波速的速度从北东向西南方向传播了约1 km。更多还原

【Abstract】 By considering 1D finite moving source model propagating unilaterally, the corner frequency is employed to determine the azimuth of rupture propagation direction and source parameters of the July 20, 1995 M_L4.1 Shacheng Earthquake, Hebei Province, such as rupture direction, rupture velocity and fault length, by means of a least-squares approach. The results show that the azimuth angle of the fault plane for this event is about 224°, consistent with aftershock distribution and the NE nodal plane of focal mechanism solution. The seismic Mach number v/c is about 1.85, which means that the average rupture velocity is greater than that of S-wave. Given the velocity of S wave 3.5 km/s, the fault length is about 1.0 km. So the rupture propagated about a length of 1.0 km along the direction from NE to SW at a super velocity of S wave.更多还原