Crustal structure of the mid-ocean ridges: 5. Heat flow through the Atlantic Ocean floor and convection currents
309
Citation
32
Reference
10
Related Paper
Citation Trend
Abstract:
One hundred and seventy-nine Lamont Geological Observatory heat-flow measurements in the Atlantic Ocean and the Caribbean Sea are presented; their reliability is carefully estimated. Together with 197 other measurements, they are used to describe the broad regional pattern of heat flow in the Atlantic Ocean. The average heat flow over the mid-Atlantic ridge is within 20% of the heat flow of the basins, and the absence of a wide heat-flow maximum in the observed values precludes the possibility of continuous continental drift during the Ceno-zoic by the spreading-floor mechanism in the Atlantic Ocean. In contrast, the excess of heat flow measured over the East Pacific rise is consistent with the existence of large convective transfer of heat in the underlying mantle.Keywords:
Seabed
Heat flow
Instability of seabed due to wave action may cause serious damages to coastal infrastructure. The wave-induced instantaneous liquefaction near and around a structure, may impact the stability and capacity of foundation elements. The wave-seabed interaction has been mostly studied based on decoupled analysis for the flat or slightly sloping seabed (slope less than five degrees). However, some of marine structures, near shore may be built on (or anchored to) seabed with considerable slopes. In this paper, the response and instability of the sloping seabed supporting a marine structure and subjected to surface waves is evaluated. The scope included developing a numerical model using a fully coupled approach. Biot's equations of the seabed in conjunction with governing equations for other domains (structure and fluid regions) are solved simultaneously using finite element method. The instability of seabed due to wave-induced instantaneous liquefaction around the marine structure is evaluated and the effect of slope on the extent of liquefied zone is examined. The results indicated that seabed response and the extent of liquefied zone near the structure are reduced with increasing steepness of seabed. The effect of various slope steepness and soil parameters on the extent of the liquefied zone is characterized and discussed.
Seabed
Biot number
Wave loading
Cite
Citations (6)
To provide a computational framework for simulating fluid-sediment-seabed interactions, a three-dimensional coupled fluid-sediment-seabed interaction model is developed and applied to seabed response under regular waves and local scouring from tsunami run-up. For the seabed response under regular waves, the computational capability of the model is demonstrated from comparison with analytical solutions in terms of pore-water pressure and the displacement of the seabed skeleton. For the local scouring from tsunami run-up, numerical results show that the model can compute the seabed response during the onset of the local scouring, and suggest that the model is a useful tool for analyzing and evaluating a general complex fluid-sediment-seabed interaction phenomenon in the marine environment.
Seabed
Cite
Citations (7)
Seabed
Wave loading
Cite
Citations (14)
Detailed suites of heat-flow measurements have been completed at four sites on and to the east of the southern end of the Blake-Bahama outer ridge in the north-west Atlantic on ocean crust which ranges in age from roughly 115 to 155 Ma. The principal purpose of these measurements was to compare instrumental techniques and to examine the decay of heat flow with age on old ocean floor.
Heat flow
Mid-Atlantic Ridge
Thermal state
Cite
Citations (43)
Wen, F. and Wang, J.H., 2015. Response of layered seabed under wave and current loading.Wave and other environmental loadings in the ocean are the main factors affecting seabed stability and the safety of marine structures. Most previous literature has considered seabed response in a layered seabed under wave loading or in a single soil layer only under combined wave and current loading. In this article, a two-layered seabed, subjected to combined wave and current loading, is considered. The influence of currents on the stratified seabed response is investigated initially. The results indicate that a following current will aggravate the instability of the seabed, either in the form of liquefaction or shear failure. The effects of stratification on the seabed response were also studied. Numerical results reveal that upper layer of the seabed will become more stable as the permeability ratio (k1 : k2) increases, where k1 and k2 are the permeability of upper and lower layer of the seabed, respectively. The thickness of each layer of the seabed also affects its stability. For example, the upper layer is apt to be more unstable when the thickness of the lower layer of the seabed (h2) is equal to about one-fifth of the wave length (L/5). Analysis of the seabed reformation in relation to engineering practice shows that replacing or adding a layer onto the original seabed can both prevent liquefaction effectively, and the approach of adding a layer has the better potential to prevent liquefaction, but those treatments have a lesser effect on the maximum depth of shear failure in the original seabed.
Seabed
Stratification (seeds)
Wave loading
Cite
Citations (10)
Seabed
Wave loading
Cite
Citations (24)