TRIGGERING FACTORS FOR SEISMIC ACTIVITY IN PRIAMURYE

This study focused on the annual distribution of seismic activity in Priamurye. An increase in the released seismic energy was identified (M≥3) in 1970-1975, 1985-1986, 1994-1995, and 2003-2005, which corresponds to the peaks of seismicity reported worldwide suggesting that a global process, such as a change in the planet rotation speed, is involved in the initiation of sufficiently strong earthquakes under intraplate conditions of Priamurye. The maximum release of seismic energy occurs during the time intervals when the frequency value, and hence the rotation speed of the planet, is minimum or maximum, which allows this process to be considered an important factor for triggering an increase in seismicity of the region. The energy distribution of weak earthquakes by year (M<3), except for seismicity peaks characteristic of relatively strong events, shows an increase in seismic activity in 1980-1983, 1990, 1998, 2000-2001, and 2007, which corresponds to the periods of increased activity of deep-focus earthquakes in the Pacific subduction zone. This fact allows seismic activity in the Pacific subduction zone to be considered an additional factor for triggering weak seismicity in Priamurye.