| Summary: | The Laptev Sea region is one of the very few places on Earth where mid-ocean spreading centres continue into continental rift zones. The Gakkel Ridge, the active spreading centre in the Eurasia Basin of the Arctic Ocean, is characterized by well-defined seismicity close to its axial graben. In contrast below the Laptev Sea Shelf, which consists of a series of sediment filled grabens (500 km wide, 700 km long), only more diffuse seismic activity is observed. The pre-rift basement in the Laptev Sea is most probably formed by Late-Paleozoic and Late-Mesozoic fold belts. The Laptev Rift Basin is filled with Upper Cretaceous and Cenozoic sediments of variable thickness (1.5 to 14 km). The westernmost limit of seismicity is located close to edge of thick lithosphere of the Siberian Shield, which indicates some structural control on the recent tectonic activity. Focal depths are mainly
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