Research by scientists affiliated with the Earth Institute at Columbia ...( h the local geology. Felix Waldhauser ...),Health

Dr. Waldhauser with colleages Bill Ellsworth and David Oppenheimer of the US Geological Survey, will also be discussing research on the recent Parkfield M6 earthquake in Central California that occurred on September 28, 2004.

Oceanography
THE HOW AND WHY OF OCEAN FLOOR GAS BLOWOUT STRUCTURES
Along the U.S. Atlantic margin are sites where giant methane gas explosions have occurred, and other places that are actively emitting methane as well as fluid from under the seafloor. Oceanographers from the Lamont Doherty Earth Observatory and elsewhere conducted surveys of these structures aboard the R/V Cape Hatteras in July, 2004. These surveys provided the data for several Earth Institute scientists to take a closer look at these large-scale gas blowout features. In several presentations, scientists discuss new discoveries based on data collected during the July voyage, such as correlations between the blowouts, methane gas emissions, and marine life, and links between fluid expulsion and slope stability. Jeffrey Weissel, Doherty Senior Scholar, LDEO (845-365-8818, jweissel@ldeo.columbia.edu).

OCEAN MIXING IN UNDERSEA CANYONS NEAR A MID-OCEAN RIDGE
Ocean circulation depends on dense water sinking, balanced by more buoyant water rising elsewhere. The authors of this study discuss their finding that a large portion of this mixing occurs in underwater canyons as water flows across sills within the canyons. In previous studies it has been suggested that the enhanced mixing is primarily caused by breaking internal waves forced by tidal flows, but now it appears that sill-related mixing in canyons seems to be at least as important as tidal mixing. Andreas Thurnherr, Doherty Asso
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Contact: Mary Tobin
mtobin@ldeo.columbia.edu
845-365-8607
The Earth Institute at Columbia University
13-Dec-2004