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Biomes and Regions of Northern Eurasia
The Far East
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Tectonics and Endogenic Processes
From the tectonic point of view, the Far East has the following characteristics:
- 1. It is positioned between the continental and the oceanic plates.
- 2. A mosaic structure of the Earth's crust.
- 3. The contemporary endogenic processes (seismic activity and volcanism) are of high
intensity.
- 4. Strong geomorphical contrasts: close proximity of deep oceanic depressions and high
mountains.
- 5. Complex coastline.
The main factor determining the dynamics of the Pacific tectonic belt is the subduction
of the oceanic plates under the Asian continent (Zonenshain et al., 1990; Tektonosfera,
1992). There are two tectonic belts within the Pacific rim: the Sikhote-Alin-Sakhalin
belt, which encompasses the Sikhote-Alin mountains and the island of Sakhalin and has
mainly a Mesozoic history, and the Koryak-Kamchatka belt, which includes structures
positioned between the Okhotsk-Chukotka volcanic belt and the Pacific Ocean (i.e., the
Kamchatka peninsula and the Kuril islands). The subduction of the Pacific Plate at a rate
of approximately 10 cm a-1 results in the active contemporary tectonics of the
Koryak-Kamchatka belt. At present, 313 terrestrial and 105 submarine volcanoes of
different ages exist in the region. Of those, 62 are active, which makes the Russian Far
East the major centre of volcanic activity outside Java (Sergeev and Krasny, 1987). This
is a perfect example of accretional tectonics which includes a number of volcanic belts of
various ages corresponding to ancient island arcs. The movement of the arcs was controlled
by the position of subduction zones and of alien blocks (exotic terrains) which has
resulted in the contemporary mosaic tectonics of the region. Tectonics and geology are
discussed in greater detail in the regional sections of this chapter.
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