On seismic mapping and modeling of near-surface sediments in polar areas
A knowledge of permafrost conditions is important for planning the foundation of buildings and engineer-ing activities at high latitudes and for geological map-ping of sediment thicknesses and architecture. The freez-ing of sediments is known to greatly affect their seismic velocities. In polar regi...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.1026.4032 2023-05-15T15:11:55+02:00 On seismic mapping and modeling of near-surface sediments in polar areas The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1026.4032 http://geophysics.geoscienceworld.org/content/gsgpy/68/2/566.full.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1026.4032 http://geophysics.geoscienceworld.org/content/gsgpy/68/2/566.full.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://geophysics.geoscienceworld.org/content/gsgpy/68/2/566.full.pdf text ftciteseerx 2016-10-30T00:03:10Z A knowledge of permafrost conditions is important for planning the foundation of buildings and engineer-ing activities at high latitudes and for geological map-ping of sediment thicknesses and architecture. The freez-ing of sediments is known to greatly affect their seismic velocities. In polar regions the actual velocities of the upper sediments may therefore potentially reveal wa-ter saturation and extent of freezing. We apply various strategies for modeling seismic velocities and reflectiv-ity properties of unconsolidated granular materials as a function of water saturation and freezing conditions. The modeling results are used to interpret a set of high-resolution seismic data collected from a glaciomarine delta at Spitsbergen, the Norwegian Arctic, where the upper subsurface sediments are assumed to be in transi-tion from unfrozen to frozen along a transect landward from the delta front. To our knowledge, this is the first attempt to study pore-fluid freezing from such data. Our study indicates that the P- and S-wave veloci-ties may increase as much as 80–90 % when fully, or almost fully, water-saturated unconsolidated sediments freeze. Since a small amount of frozen water in the voids of a porous rock can lead to large velocity increases, the freezing of sediments reduces seismic resolution; thus, the optimum resolution is obtained at locations where the sediments appear unfrozen. The reflectivity from boundaries separating sediments of slightly differ-ent porosity may depend more strongly on the actual sat-uration rather than changes in granular characteristics. For fully water-saturated sediments, the P-wave reflectiv-ity decreases sharply with freezing, while the reflectivity becomes less affected as the water saturation is lowered. Thus, a combination of velocity and reflectivity informa-tion may reveal saturation and freezing conditions. Text Arctic permafrost Spitsbergen Unknown Arctic |
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English |
description |
A knowledge of permafrost conditions is important for planning the foundation of buildings and engineer-ing activities at high latitudes and for geological map-ping of sediment thicknesses and architecture. The freez-ing of sediments is known to greatly affect their seismic velocities. In polar regions the actual velocities of the upper sediments may therefore potentially reveal wa-ter saturation and extent of freezing. We apply various strategies for modeling seismic velocities and reflectiv-ity properties of unconsolidated granular materials as a function of water saturation and freezing conditions. The modeling results are used to interpret a set of high-resolution seismic data collected from a glaciomarine delta at Spitsbergen, the Norwegian Arctic, where the upper subsurface sediments are assumed to be in transi-tion from unfrozen to frozen along a transect landward from the delta front. To our knowledge, this is the first attempt to study pore-fluid freezing from such data. Our study indicates that the P- and S-wave veloci-ties may increase as much as 80–90 % when fully, or almost fully, water-saturated unconsolidated sediments freeze. Since a small amount of frozen water in the voids of a porous rock can lead to large velocity increases, the freezing of sediments reduces seismic resolution; thus, the optimum resolution is obtained at locations where the sediments appear unfrozen. The reflectivity from boundaries separating sediments of slightly differ-ent porosity may depend more strongly on the actual sat-uration rather than changes in granular characteristics. For fully water-saturated sediments, the P-wave reflectiv-ity decreases sharply with freezing, while the reflectivity becomes less affected as the water saturation is lowered. Thus, a combination of velocity and reflectivity informa-tion may reveal saturation and freezing conditions. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
title |
On seismic mapping and modeling of near-surface sediments in polar areas |
spellingShingle |
On seismic mapping and modeling of near-surface sediments in polar areas |
title_short |
On seismic mapping and modeling of near-surface sediments in polar areas |
title_full |
On seismic mapping and modeling of near-surface sediments in polar areas |
title_fullStr |
On seismic mapping and modeling of near-surface sediments in polar areas |
title_full_unstemmed |
On seismic mapping and modeling of near-surface sediments in polar areas |
title_sort |
on seismic mapping and modeling of near-surface sediments in polar areas |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1026.4032 http://geophysics.geoscienceworld.org/content/gsgpy/68/2/566.full.pdf |
geographic |
Arctic |
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Arctic |
genre |
Arctic permafrost Spitsbergen |
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Arctic permafrost Spitsbergen |
op_source |
http://geophysics.geoscienceworld.org/content/gsgpy/68/2/566.full.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1026.4032 http://geophysics.geoscienceworld.org/content/gsgpy/68/2/566.full.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766342694798360576 |