Initial Reports of the Deep Sea Drilling Project - Volume 88

This volume covers Leg 88 of the cruises of the Drilling Vessel Glomar Challenger. The northwest Pacific Ocean is the most active earthquake zone in the world. More than 20% of the world's seismic energy is released in the Aleutian-Kurile seismic zones, where the Pacific Plate is actively being subducted. Seismic systems placed on islands in the Aleutians and in Japan are on the overriding plate and are thus subject to the high noise levels and complexities of island arc structure. Islands on the Pacific Plate, such as Midway and Wake, tend to be seismically noisy and are relatively far from the sources of activity. Ocean bottom seismometers are temporary, subject to ocean current noise, and can be poorly coupled to the ocean floor. The prime objective of DSDP Leg 88 was to deploy two permanent borehole seismometers in the seafloor off the Kuriles. The first priority was to deploy a three-component seismometer, the Marine Seismic System (MSS), built by the Defense Advanced Research Projects Agency (DARPA), in a reentry hole at DSDP Site 581. The Hawaii Institute of Geophysics (HIG) seismic system was to be placed in a hole nearby and a hole was to be piston cored for paleoenvironmental studies. No logging was planned but tests on a wireline reentry system were made. Leg 88 began in Hakodate, Japan in August 1982 and ended in Yokohama, Japan in September 1982.