Recent geodynamic regime of the Eurasia – North American interplate boundary: evidences from seismology of Arctic

The paper considers seismological evidences on a geodynamic regime in the Arctic segment of the interplate boundary between Eurasian and North American lithosphere plates. A scope of earthquakes occurred in the Mon, Knipovich and Gakkel mid-ocean ridge belts (MORB) has been made, and distribution of double-couple (DC) and non-double-couple (NDC) sources has been evaluated. As revealed, the DC events, caused by shearing tectonic movements, prevail among earthquakes in all MORBs. In the Arctic MORBs with ultra low speed of spreading the NDC earthquakes, caused by normal rifting or volcanic eruptions, are responsible for 9 % seismic energy release only, whereas in the Mon Ridge (North Atlantic spreading belt with the average speed of extension about 3 cm per annum) their contribution is 5 times higher. Thus, the seismological data give evidences that the Arctic segment of the interplate boundary between Eurasian and North American lithosphere plates belongs recently to the transform geodynamic type, and only in the North Atlantics (within the Mon Ridge) a divergent type is still alive.