HR: 1340h
AN: S13B-1050    [Abstracts]
TI: Construction of a 3D seismic velocity model for the Barents Sea region using sediment vs. crystalline crust thickness relationships
AU: * Ritzmann, O
EM: oliver.ritzmann@geo.uio.no
AF: Department of Geoscience - University of Oslo, P.O. Box 1047 Blindern , Oslo, 0482 Norway
AU: Faleide, J
EM: j.i.faleide@geo.uio.no
AF: Department of Geoscience - University of Oslo, P.O. Box 1047 Blindern , Oslo, 0482 Norway
AU: Bungum, H
EM: hilmar.bungum@norsar.no
AF: Norsar, P.O. Box 53, Kjeller, 2027 Norway
AU: Maercklin, N
EM: nils.maercklin@norsar.no
AF: Norsar, P.O. Box 53, Kjeller, 2027 Norway
AU: Schweitzer, J
EM: johannes@norsar.no
AF: Norsar, P.O. Box 53, Kjeller, 2027 Norway
AU: Mooney, W D
EM: mooney@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Detweiler, S T
EM: shane@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Leith, W S
EM: wleith@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AB: 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 Basis of this model is a recent compilation of seismic velocities taken from published wide-angle profiles, unpublished ESP profiles and additional gravity modeling along deep MSC-profiles.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).
DE: 7219 Nuclear explosion seismology
DE: 7205 Continental crust (1242)
DE: 3025 Marine seismics (0935)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting