North American-Eurasian Plate Boundary in northeast Asia

Abstract

The intracontinental portion of the boundary between the North American and Eurasian plates can be identified ort the basis of seismicity, recent tectonics, and earthquake focal mechanisms. The simplest plate geometry that can explain these data involves a North American-Eurasian boundary that extends from the Nansen ridge through a broad zone of deformation in northeast Asia to the Sea of Okhotsk and thence southward through Sakhalin and Hokkaido to a triple junction in the Kuril-Japan trench. Such a configuration can account quantitatively for the slip vectors derived from earthquake mechanisms in Sakhalin and Hokkaido. On the basis of new slip vector data the North American-Eurasian angular velocity vector is revised only slightly from previous determinations. The intracontinental plate boundary is diffuse and may be controlled by ancient plate sutures. Deformation within about 10° of the rotation pole, which lies very near the boundary, cannot be modeled by rigid plate tectonics. These characteristics of intracontinental plate boundaries are related to the greater thickness and heterogeneity of continental lithosphere and to the influence of continents on the plate tectonic driving forces.