Abstract
We present a 3D seismic velocity model for the extended Barents Sea
region, including Svalbard, Novaya Zemlya, the Kara Sea and the Kola-Karelia
Regions. The purpose of developing a higher-resolution velocity model
is to improve generally the seismic event localization in the target
region. The model should improve the future monitoring facilities
and the accompanied travel-time modeling. Initial testing of the
model will base on the modeling of a series of seismic ground-truth
events recorded by the surrounding stations. The model has a spatial
resolution of 50x50 km and includes 1490 nodes. Each node is filled
with a 5-layer crustal model (plus water/ice- and additional mantle
layers): Nodes within the oceanic and continental domains bear two
sedimentary layers (low/high vp) and three 'crystalline' crustal
layers(low/intermediate/high vp). Basis of this model is a recent
compilation of seismic velocities taken from published wide-angle
profiles,unpublished ESP profiles and additional gravity modeling
along deep MSC-profiles. Over 700 1D velocity profiles are collected.
In order to interpolate the velocity/depth-information from the randomly
distributed 1D profiles on the equal-spaced grid, the following technique
was applied: Analyzing the database, we found a strong linear trend
between the total thickness of the sediment layers and the remaining
crystalline crust within pre-defined continental provinces (e.g.
distinct sedimentary basins, plateaus, basement highs, etc.). Area-wide
depth-to-basement information, based on the integrated analysis of
seismic, gravity and magnetic data is used to calculate the crystalline
and total crustal thicknesses as functions of sediment thickness.
The mean seismic velocities and thickness-rates for each of the 5
crustal layers are calculated from the compiled database. Analysis
of the regressions show that about 75-90\% of the data input is fitted
by the calculated functions with a maximum of 20\% deviation relative
to its total thickness. The compiled database provides further excellent
statistical background for composition of crystalline crustal rocks
in the target region. The overall distribution of seismic velocities
within crystalline crust shows a clear bimodal structure with velocity
peaks at 6.4 and 6.8 km/s. First modeling tests along four selected
transects were carried out to evaluate the constructed 3D seismic
model. According to the tests travel-time deviations can exceed 2
s at distances of 300-800 km (by comparison to a standard 1D model).
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