利用sPL震相测定2017年河北临城ML 4.4地震震源深度

2017年9月4日河北临城地区发生M_L 4.4地震，为得到准确的震源深度，根据sPL震相基本特征，对震中距20-70 km范围内8个地震台站波形数据进行处理，在其中4个地震台观测到明显的sPL震相，利用频率-波数（F-K）方法，计算其理论波形图，与处理后的观测波形拟合对比，得到震源深度范围，与TDMT-INV方法、PTD方法及河北测震台网编目等结果基本一致，表明利用sPL震相测定河北临城M_L 4.4地震震源深度可靠，其深度范围为10-11 km。

Determination of focal depth of Lincheng ML 4.4 earthquake in Hebei province by sPL seismic phase

On September 4, 2017, a M_L 4.4 earthquake occurred in Lincheng city, Hebei Province. To get the exact focal depth of the earthquake, the waveform data of 8 stations which in the range of 20-70 km from the earthquake epicenter were processed, and the apparent sPL seismic phase was observed at 4 stations according to the basic characteristics of sPL seismic phase. The depth range of this earthquake is obtained by fitting and contrasting the theoretical waveforms which calculated by the method of the frequency-wavenumber (F-K) and the processed actual waveforms. Compared with the results calculated by the method of TDMT-INV and PTD, and the catalogue result of Hebei Seismic Network, the four results are basically the same. Showing that it is reliable to use the sPL seismic phase to determine the focal depth of Lincheng M_L 4.4 earthquake, and the range of the focal depth is about 10-11 km.