30-Day Ocean-Bottom Seismograph: Modification and Testing of Nineteen Ocean-Bottom Seismographs

摘要

Dallas modifications and tests, Albuquerque land tests, shallow and deep water tests off the coast of California, and antenna tests were run to prove that the Ocean-Bottom Seismograph is a practicable seismograph. Dallas modifications included pressure switches added to the radio transmitter and the beacon light. A new high-precision motor was added to the tape recorder. Pressure transducer sensitivity was increased by approximately 20 db. The trigger board was redesigned for sonar recall. The U-joint, battery boxes, bottom and side plugs, and secondary release were also modified, and an input filter was added. Albuquerque land tests showed almost exact duplication between OBS data and that from adjacent reference seismometers. Shallow and deep water tests showed that the unit was basically reliable, but showed a resonance problem. The consequent antenna tests resulted in a switch to wrap around antennas to solve the ocean current-induced resonance. Clock tests were run to test the accuracy of the clocks at 3C and 25C and to measure the thermal time lag. (Author)