Effect of gas hydrates melting on seafloor slope instability

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doi: 10.1016/j.margeo.2004.10.015
Author(s): Sultan, Nabil; Cochonat, P.; Foucher, J. P.; Mienert, Juergen
Author Affiliation(s): Primary:
IFREMER Brest, Departement de Geosciences Marines, Plouzane, France
Other:
University of Tromso, Norway
Volume Title: COSTA, continental slope stability; a contribution to the Energy, Environment and Sustainable Development Programme FP5 of the European Commission, number EVK3-CT-1999-00006
Volume Author(s): Mienert, Juergen, editor
Source: COSTA, continental slope stability; a contribution to the Energy, Environment and Sustainable Development Programme FP5 of the European Commission, number EVK3-CT-1999-00006, edited by Juergen Mienert. Marine Geology, 213(1-4), p.379-401. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. Includes appendices. 36 refs.; illus., incl. 1 table, sketch map
Summary: We present a theoretical study of the thermodynamic chemical equilibrium of gas hydrate in soil by taking into account the influence of temperature, pressure, pore water chemistry, and the mean pore size distribution. The model uses a new formulation based on the enthalpy form of the law of conservation of energy. The developed model shows that due to a temperature and pressure increase, hydrates may dissociate at the top of the hydrate occurrence zone to ensure a chemical equilibrium with the surrounding bulk water. This original result confirms what has been already shown through experiments. The second part of the paper presents an application of the model through a back-analysis of the giant Storegga Slide on the Norwegian margin. Two of the most important changes during and since the last deglaciation (hydrostatic pressure due to the change of the sea level and the increase of the sea water temperature) were considered in the calculation. Simulation results show that melting of gas hydrate due to the change of the gas solubility can be at the origin of a retrogressive failure initiated at the lower part of the Storegga slope. Once again, the developed model leads to predictions, which are supported by laboratory experiment results, but contradictory to previous interpretations and beliefs considering that hydrate dissociation occurs only at the bottom of the gas hydrate stability zone.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 22 Environmental Geology; Aliphatic hydrocarbons; Alkanes; Atlantic Ocean; Bathymetry; Concentration; Continental margin; Cores; Data processing; Digital simulation; Effects; Europe; Gas hydrates; Geologic hazards; Hydrocarbons; Leg 104; Marine sediments; Melting; Methane; North Atlantic; Northeast Atlantic; Norway; Numerical models; ODP Site 644; Ocean Drilling Program; Ocean floors; Organic compounds; Phase equilibria; Pore pressure; Prediction; Pressure; Risk assessment; Safety; Scandinavia; Sediments; Shear strength; Slope stability; Storegga Slide; Temperature; Thermodynamic properties; Western Europe
Coordinates: N620000 N670000 E0060000 E0010000
Record ID: 2005033932
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands