School of Geophysics and Measurement-control Technology East China University of Technology Nanchang 330013 China;
Institute of Disaster Prevention Sanhe 065201 Hebei China;
Hebei Key Laboratory of Earthquake Dynamics Sanhe 065201 Hebei China;
Institute of Geophysics China Earthquake Administration Beijing 100081 China;
Earthquake Administration of Hebei Province Shijiazhuang 050021 China;
China Earthquake Networks Center Beijing 100045 China;
School of Geomatics East China University of Technology Nanchang 330013 China;
Institute of Disaster Prevention Sanhe 065201 Hebei China;
