THE GREAT EARTHQUAKE AND THE CONJUGATE TECTONIC MOTION
Zhang Sichang(Yunnan Seismological Bureau)
Taking six great earthquakes occurred recently in China as examples a kind of rupture mode of great continental earthquake with shallow focus is discussed. By analysing the data from ground rupture zone, the solution of the P wave initial motion, the direction of mojor axes of the isoseismal lines, the time-space distribution of aftershocks and so on, the great earthquake sequences show a characteristic of 2-way rupture with conjugate nature.The development of two conjugate rupture plane shows itself always asymmetric nature depending on the tectonic feature in a certain seismic area. It is suggested that the seismic activities before some great major shocks are distributed along two nodal plane of P wave initial motion. The study of geological feature of the conjugate structures would be significant to predict major shock and strong aftershock.