U.S.-Germany Cooperative Research on Sediment Acoustic Properties

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9214096 Wilkens This award supports Professor Roy H. Wilkens and a graduate student from the University of Hawaii for international collaboration with Dr. Jurgen Mienert and others of GEOMAR, a marine geological institute in Kiel, Germany. These two groups share an interest in the measurement and interpretation of acoustic properties and the acoustic stratigraphy of the seafloor under the deep ocean. They plan to investigate in great detail the variations in several physical properties in the upper zone of these seafloor sediments. The German research group has been developing geophysical instrumentation complementary to some being developed at the University of Hawaii. Professor Wilkens and his student have been invited to join in the planning for and accompany the Germans on at least one cruise aboard a German research vessel. Both U. S. and German scientific programs will benefit greatly from the proposed combination of measuring techniques and oceanographic expertise. The upper ten meters of the seafloor contain the largest gradients in physical and acoustic proerties in the sediment- seawater system. Within this zone, porosity may change by 20- 30% and density may vary by as much as 50% Modern geophysical instrumentation such as that being developed by the participating research groups is making it possible to locate precisely and sample the discontinuities where sediment composition or microstructure changes. Examining such samples reveals the nature of the changes in the sediment and can provide evidence of changes in paleo-environmental conditions. Such data are extremely valuable in studies of local and global climate change. ***