Abstract:

Deep earthquakes（including intermediatefocus and deepfocus earthquakes）play an important role in the study of structure of Earth deep interior, plate motion and dynamical mechanisms. Since the first discovery of deep earthquakes by Wadati，they have attracted extensive attention worldwide and had many high quality papers during this eighty years. However，the mechanism of deep earthquakes is still an unsolved problem. Now, it is commonly accepted that dehydration embrittlement is the mechanism of intermediatefocus earthquakes while transformational faulting is responsible for the deepfocus earthquakes. Although some researchers thought that the adiabatic shear instability is also suitable for intermediatefocus and deepfocus earthquakes, it needs more experimental evidence. Northeast China, located in the border of the Pacific Ocean Seismic Area, is also the only deepfocus earthquake zone in China. Combing the study of the structural geology of Earth surface, mineral rock physics, deep exploration, high temperature and high pressure experiments and numerical simulation analysis is an effective way to solve the problem of the mechanism of deep earthquakes. To strengthen the research of the mechanism of deepfocus earthquakes in the northeast area of China and western Pacific plate subduction is of a great significance for further studying the evolution of the tectonic patterns.

Key words: deep earthquakes, subduction zone, dehydration embrittlement, transformational faulting, adiabatic shear instability, deep earthquakes in northeast China