New Data on Seismotectonics of the Laptev Sea from Observations by Ocean Bottom Seismographs

Abstract

The results of new local seismic observations in the Laptev Sea obtained using ocean bottom seismographs were compared with actual data from global and regional earthquake catalogs. Most earthquake epicenters on the Laptev Sea shelf are grouped into several clusters located within the East Laptev province of horsts and grabens and enclosed between two extension detachments. The first one marks the eastern boundary of the Ust–Lena and Omoloi rift systems, and the second one is the eastern boundary of the Anisin, Zarya, and Belkovskii-Svyatoi Nos rift chains. At the same time, the linear zone of epicenters confined to the Gakkel Ridge, when moving to the shelf, shifts along the Khatanga–Lomonosov fault zone to the northeast in the direction of the second extension detachment, which probably remains the only active one. The spatial distribution of earthquakes in the Laptev Sea, taking into account the epicenters of micro- and weak seismic events on the shelf, does not have sufficiently clear boundaries that determine the contours of the previously assumed lithospheric microplate.