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The boundary between Okhotsk microplate and Pacific plate is a subduction zone, where the Pacific plate subducts beneath the Okhotsk Plate. Many strong megathrust earthquakes occurred here, some of them among the largest on world record, including the Kamchatka earthquakes of 1737 (estimated M9.0~9.3) and 1952 (M9.0).
The basis for defining this tectonic boundary is the occurrence of large magnitude 7 or greater earthquakes along a linear zone from offshore Niigata Prefecture to off the west coast of Hokkaido. [7] Following the 1983 Nihonkai-Chubu earthquake , the idea of a young plate boundary was proposed, but its mechanism is unknown—it has been ...
Thrust faults are characteristic of areas where the Earth's crust is being compressed by tectonic forces. [11] Megathrust faults occur where two tectonic plates collide. When one of the plates is composed of oceanic lithosphere, it dives beneath the other plate (called the overriding plate) and sinks into the Earth's mantle as a slab.
Where the plates meet, their relative motion determines the type of plate boundary (or fault): convergent, divergent, or transform. The relative movement of the plates typically ranges from zero to 10 cm annually. [5] Faults tend to be geologically active, experiencing earthquakes, volcanic activity, mountain-building, and oceanic trench formation.
During the late Neogene period (23.03-2.58 million years ago), the Japan Trench underwent a period of plate convergence between the Pacific and Okhotsk plates. Based on the sediment sequence during this time, there appears to have been little net accretion of sediment onto the overlying plate as well as evidence of mild erosion at the base of the convergent margin.
Around 23 million years ago, western Japan was a coastal region of the Eurasia continent. The subducting plates, being deeper than the Eurasian plate, pulled parts of Japan which become modern Chūgoku region and Kyushu eastward, opening the Sea of Japan (simultaneously with the Sea of Okhotsk) around 15–20 million years ago, with likely freshwater lake state before the sea has rushed in. [4 ...
Continental-continental divergent/constructive boundary Oceanic divergent boundary: mid-ocean ridge (cross-section/cut-away view). In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.
Convergent boundaries are areas where plates move toward each other and collide. These are also known as compressional or destructive boundaries. Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This ...