HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) References Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by CRANFORD, M. D. Articles by BROWN, B. T. Search for Related Content GeoRef GeoRef Citation

A direct-recording ocean-bottom seismograph

SCHOOL OF OCEANOGRAPHY OREGON STATE UNIVERSITY, CORVALLIS, OREGON 97331

Abstract

A direct-recording ocean-bottom seismograph featuring small size and low cost has been constructed and operated in the deep ocean. The design consists of a cylindrical instrument package 15 cm in diameter and 53 cm long. Signals from a gimbal-mounted 2-Hz vertical geophone and a hydrophone are amplified and direct-recorded at different gain levels on three channels of 6.4-mm wide magnetic tape. BCD-coded time pulses, generated from a crystal oscillator signal, are recorded on the fourth channel. The instrument has its maximum displacement response at 17 Hz. Tape consumption is 22 m/day (0.01 ips) from 12.7-cm reels permitting continuous recording for up to 12.5 days. CMOS electronics are used throughout and, together with a low-power tape drive motor, the unit requires less than 100 mW of power. This permits long recording times from 9 D-cell alkaline batteries. Syntactic foam flotation, good to 6400 m, permits a low-profile design 1.0 m long and 0.7 m high. It weights 114 kg in air and descent and rise rates are 0.64 m/sec. For retrieval, an expendable base plate is released by a cable cutter on command from a clock comparator circuit. Data playback is at 10 to 100 times recorded speed.

Footnotes

^* Present address: Tektronics Inc., Beaverton, Oregon 97005.

This article has been cited by other articles:

				C. D. LINDHOLM and P. C. MARROW Ocean bottom seismometers in the northern North Sea: Experience and preliminary results with the Statfjord OBS Bulletin of the Seismological Society of America, August 1, 1990; 80(4): 1014 - 1025. [Abstract] [PDF]