[PDF] Seismological Investigations Of A West Antarctic Ice Stream eBook

Author : Tarun Luthra
Publisher :
Page : pages
File Size : 41,74 MB
Release : 2017
Category :
ISBN :

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An accurate knowledge of the subglacial system is key in elucidating the mechanisms of ice stream motion and overall mass balance of the Antarctic Ice Sheet. Ice streams, owing to their geometry and low surface slopes, generate really low driving stress, thus typically require an extensive deformable subglacial sediment layer to allow fast flow conditions. This thin layer of sediment is highly sensitive to subglacial water pressure, which, if reduced, can dramatically alter the flow dynamics of ice streams. The flow regime of Whillans Ice Stream and Kamb Ice Stream highlight these basal conditions. Kamb Ice Stream stagnated about 150 years ago while current observations of the Whillans Ice Stream show that the ice stream is decelerating in the past few decades. Both attribute their current flow conditions to the presence of areas of high basal drag or the so-called sticky spots, which inhibit fast ice stream flow. This subglacial interface is highly influenced by the sediment porosity, fluid pressure, and water content which ultimately defines its overall strength in restricting the ice-stream flow. In this thesis, I employ the seismic amplitude analysis technique to study the subglacial interface of these two ice streams. The seismic amplitude analysis provides an insight into the subglacial regimes of ice stream flow in Antarctica. The knowledge about this subglacial interface and ground truthing of bed conditions is essential for the ice sheet models and discerning ice dynamics to understand the future evolution of these ice streams.

Author : Masaki Kanao
Publisher : BoD – Books on Demand
Page : 118 pages
File Size : 30,81 MB
Release : 2018-10-10
Category : Science
ISBN : 1789235685

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Seismology in polar regions (Arctic and Antarctic) allows us to study the static condition and high-latitude dynamics of the Earth. This book covers the recent developments in seismology in polar regions; observations and networks; international collaboration; heterogeneous structure and dynamics of the lithosphere; deep Earth's interiors observed from high latitudes; characteristics of seismicity and seismic wave propagation; and global tectonics in terms of Earth's history, including the interdisciplinary studies on the interaction between Earth's spheres. Since the International Polar Year (IPY) in 2007/2008 was the most exciting campaign launched within contemporary polar studies, this book observes recent seismological achievements by the IPY, specifically focusing on the seismic signals near the surface associated with cryosphere dynamics and evolution. Topics on cryoseismology, such as glacial earthquake activities, are viewed in terms of global warming. Moreover, observational experiments and long-term monitoring under the extreme conditions in the polar environment are also discussed.

Author : C.J. van der Veen
Publisher : Springer Science & Business Media
Page : 376 pages
File Size : 44,86 MB
Release : 2012-12-06
Category : Science
ISBN : 9400937458

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Few scientists doubt the prediction that the antropogenic release of carbon dioxide in the atmosphere will lead to some warming of the earth's climate. So there is good reason to investigate the possible effects of such a warming, in dependence of geographical and social economic setting. Many bodies, governmental or not, have organized meetings and issued reports in which the carbon dioxide problem is defined, reviewed, and possible threats assessed. The rate at which such reports are produced still increases. However, while more and more people are getting involved in the 'carbon dioxide business', the number of investigators working on the basic problems grows, in our view, too slowly. Many fundamental questions are still not answered in a satisfactory way, and the carbon dioxide building rests on a few thin pillars. One such fundamental question concerns the change in sea level associated with a climatic warming of a few degrees. A number of processes can be listed that could all lead to changes of the order of tens of centimeters (e. g. thermal expansion, change in mass balance of glaciers and ice sheets). But the picture of the carbon dioxide problem has frequently be made more dramatic by suggesting that the West Antarctic Ice Sheet is unstable, implying a certain probability of a 5 m higher sea-level stand within a few centuries.