Kanwisher
John W.
Kanwisher
John W.
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Technical ReportLake Kivu expedition : geophysics, hydrography, sedimentology (preliminary report)(Woods Hole Oceanographic Institution, 1971-07) Degens, Egon T. ; Deuser, Werner G. ; von Herzen, Richard P. ; Wong, How-Kin ; Wooding, Frank B. ; Jannasch, Holger W. ; Kanwisher, John W.In March 1971, seven members of the Woods Hole Oceanographic Institution were engaged in a multidisciplinary study of Lake Kivu. This expedition represents part of a long-range program concerned with the structural and hydrographical settings of the East African Rift Lakes and their relationships to the Red Sea and the Gulf of Aden Rifts. The program started in May 1963 with a geophysical study on Lake Malawi (von Herzen and Vacquier, 1967). Several expeditions of our Institution into the Red Sea and Gulf of Aden area in 1964, 1965 and 1966 (Degens and Ross, 1969) provided detailed geological information on the "northern" extension of the East African Rift. And finally our study of last year on Lake Tanganyika c1osed a major gap in the program; it allowed us to out1ine a model on the evolution of a rift which starts with (i) bulging of the earth's crust, (ii) block-faulting, (iii) volcanism and hydrothermal activity, and which has its final stage in (iv) sea floor spreading (Degens et al. 1971). In the case of Lake Tanganyika, only the second stage of this evolution series has been reached, i.e. block-faulting. In contrast, the Red Sea and the Gulf of Aden had already evolved to active sea floor spreading, almost 25 million years ago. Somewhere along the line between Lake Tanganyika and the Gulf of Aden must lie the "missing link" of this evolution series. Lake Kivu, almost 100 miles to the north of Lake Tanganyika is situated at the highest point of the Rift Valley and is surrounded by active volcanoes and geothermal springs. As recently as 1944, lava flows reached the lake shore. This lake was therefore, a natural choice to test our hypothesis on the origin and development of rifts. Furthermore, the occurrence of large quantities of dissolved gases, e.g., CO2 and methane, represented an interesting geochemical phenomenon worthwhile to investigate.
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Technical ReportElectromagnetic flow sensors(Woods Hole Oceanographic Institution, 1974-03) Lawson, Kenneth ; Kanwisher, John W.Flow sensors based on the principle of electromagnetic induction were investigated as alternatives to commonly used mechanical devices utilizing rotors and propellers. Prototype sensors were constructed showing considerable promise. Measurement accuracy in excess of .01 knot seems feasible with devices suited to long term battery operation. The inertial effects and many of the reliability problems inherent in moving part devices would be overcome by use of an electromagnetic sensor.