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Dynamic pore-pressure fluctuations in rapidly shearing granular materials Dynamic pore-pressure fluctuations in rapidly shearing granular materials

Results from two types of experiments show that intergranular pore pressures fluctuated dynamically during rapid, steady shear deformation of water-saturated granular materials. During some fluctuations, the pore water locally supported all normal and shear stresses, while grain-contact stresses transiently fell to zero. Fluctuations also propagated outward from the shear zone; this...
Authors
Richard M. Iverson, Richard G. Lahusen

Impacts of exploratory drilling for oil and gas on the benthic environment of Georges Bank Impacts of exploratory drilling for oil and gas on the benthic environment of Georges Bank

A 3-year monitoring program was performed to assess the impacts of exploratory drilling for oil and gas on the benthic environment of Georges Bank, an important commercial fishery region in the North Atlantic east of Massachusetts, USA. Surficial sediments were sampled for chemical and benthic infaunal analysis and bottom still photographs were taken to document bottom microtopography...
Authors
J. M. Neff, Michael H. Bothner, N. J. Maciolek, J. F. Grassle

Holocene sand shoals offshore of the Mississippi River delta plain Holocene sand shoals offshore of the Mississippi River delta plain

Offshore of the Mississippi River delta plain lies a series of Holocene sand shoals marking the position of ancient submerged shorelines associated with younger shelf-phase delta plains. These submerged shorelines represent positions when sea level stood lower than present. Short periods of rapid sea level rise during the Holocene transgression, in combination with subsidence, led to the
Authors
Shea Penland, John R. Suter, Randolph A. McBride, S. Jeffress Williams, Jack L. Kindinger, Ron Boyd

The competition between thermal contraction and differentiation in the stress history of the Moon The competition between thermal contraction and differentiation in the stress history of the Moon

The scarcity of both extension and compression features on the Moon strongly constrains the history of the lunar radius—to variations of less than ±1 km over the past 3.8 Gyr. This limit has traditionally been interpreted as requiring a delicate balance between thermal contraction of the near‐surface and expansion of a substantial cold interior region. Recent theories of lunar origin (e...
Authors
Randolph L. Kirk, David J. Stevenson

Morphology of sea-floor landslides on Horizon Guyot: application of steady-state geotechnical analysis Morphology of sea-floor landslides on Horizon Guyot: application of steady-state geotechnical analysis

Mass movement and erosion have been identified on the pelagic sediment cap of Horizon Guyot, a seamount in the Mid-Pacific Mountains. Trends in the size, shape and preservation of bedforms and sediment textural trends on the pelagic cap indicate that bottom-current-generated sediment transport direction is upslope. Slumping of the sediment cap occurred on and that the net bedload...
Authors
R. E. Kayen, W. C. Schwab, H.J. Lee, M.E. Torresan, J.R. Hein, P. J. Quinterno, L.A. Levin
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