Аннотация
Existing global and regional tomographic models have limited resolution
in the European Arctic due to the small number of seismic stations,relatively
low regional seismicity, and poor knowledge of the crustal structure.
During the last decades, new seismic stations were permanently or
temporarily installed in and around this region. However,many of
the data from these stations are not easily accessible via the international
data centers but only by direct request to various data operators.
Recently, a new crustal model of the Barents Sea and surrounding
areas had been derived in a joint project between the University
of Oslo, NORSAR and the USGS (Bungum et al. (2005), EOS 86(16), 160-161).
This model with its detailed information on crustal thickness and
sedimentary basins in the area helps to constrain the tomographic
inversion of the upper mantle velocity structure based on surface
wave data. To improve the surface wave data set in the region,we
extensively searched for broadband data from stations in the area
from the beginning of the 1970s until 2005 and were able to retrieve
surface wave observations from the data archives at NORSAR, University
of Bergen, University of Helsinki, the Kola Science Center in Apatity,and
the Geological Service of Denmark in addition to data from the data
centers of IRIS and GEOFON. Rayleigh and Love wave group velocity
measurements from 10 sec to 150 sec period obtained on these seismograms
were combined with the existing data set provided by the University
of Colorado (e.g., Levshin et al. (2001), PEPI 123, 185-204). Using
these data, we constructed a new 3-D shear velocity model of the
crust and upper mantle beneath the European Arctic which provides
higher resolution and accuracy than previous models. The new model
reveals substantial variations in shear wave speeds in the upper
mantle across the region. Of particular note are clarified images
of the mantle expression of the continental-ocean transition in the
Norwegian Sea and a deep high wave speed lithospheric root beneath
Novaya Zemlya.
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