Structural variations along the Kuril-Kamchatka trench and a possible relation to seismicity

This paper considers the results from seismic investigations of the Kuril-Kamchatka trench (KKT) using continuous seismic profiling (CSP), the common-depth point (CDP), and deep seismic sounding (DSS). The outcome is an approximate 2D seismic model that reflects the overall structure of the landward trench slope for most of the KKT, with the greatest departure of the data from the model being for the middle Kuril Islands area. A deep-seated fault has been identified in the upper part of the slope 60–80 km from the trench axis, with the fault being traceable throughout the depth interval between the seafloor and the bottom of the crust. In the portion between the fault and the trench axis the seismic velocities are lower, the gradient higher, and the crust thins rapidly seaward. The sediment thickness on the landward slope varies along the trench, reaching the maximum off the southern Kuril Islands. The structural variations along the KKT show a broad correlation with the behavior of geophysical fields and seismicity, which seems to be an expression of global tectonic processes.