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{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2024,9,16]],"date-time":"2024-09-16T15:13:59Z","timestamp":1726499639613},"reference-count":26,"publisher":"Society of Exploration Geophysicists","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["GEOPHYSICS"],"published-print":{"date-parts":[[1998,5]]},"abstract":" Induction in electrically conductive seawater attenuates the magnetotelluric (MT) fields and, coupled with a minimum around 1 Hz in the natural magnetic field spectrum, leads to a dramatic loss of electric and magnetic field power on the sea floor at periods shorter than 1000 s. For this reason the marine MT method traditionally has been used only at periods of 103<\/jats:sup> to 105<\/jats:sup> s to probe deep mantle structure; rarely does a sea\u2010floor MT response extend to a 100-s period. To be useful for mapping continental shelf structure at depths relevant to petroleum exploration, however, MT measurements need to be made at periods between 1 and 1000 s. This can be accomplished using ac-coupled sensors, induction coils for the magnetic field, and an electric field amplifier developed for marine controlled\u2010source applications. The electrically quiet sea floor allows the attenuated electric field to be amplified greatly before recording; in deep (1-km) water, motional noise in magnetic field sensors appears not to be a problem. In shallower water, motional noise does degrade the magnetic measurement, but sea\u2010floor magnetic records can be replaced by land recordings, producing an effective sea\u2010surface MT response. Field trials of such equipment in 1-km-deep water produced good\u2010quality MT responses at periods of 3 to 1000 s; in shallower water, responses to a few hertz can be obtained. Using an autonomous sea\u2010floor data logger developed at Scripps Institution of Oceanography, marine surveys of 50 to 100 sites are feasible. <\/jats:p>","DOI":"10.1190\/1.1444393","type":"journal-article","created":{"date-parts":[[2002,10,11]],"date-time":"2002-10-11T15:52:42Z","timestamp":1034351562000},"page":"816-825","source":"Crossref","is-referenced-by-count":138,"title":["Marine magnetotellurics for petroleum exploration Part I: A sea\u2010floor equipment system"],"prefix":"10.1190","volume":"63","author":[{"given":"Steven C.","family":"Constable","sequence":"first","affiliation":[{"name":"Scripps Institution of Oceanography, IGPP 0225, 8604 La Jolla Shores Drive, La Jolla, California 92093-0225."}]},{"given":"Arnold S.","family":"Orange","sequence":"additional","affiliation":[{"name":"Arnold Orange Associates, 8806 Point West Drive, Austin, Texas 78759."}]},{"given":"G. Michael","family":"Hoversten","sequence":"additional","affiliation":[{"name":"Lawrence Berkeley Laboratory, University of California, 1 Cyclotron Rd., Bldg. 90, Rm 1116, Berkeley, California 94270. Emails:"}]},{"given":"H. Frank","family":"Morrison","sequence":"additional","affiliation":[{"name":"Lawrence Berkeley Laboratory, University of California, 1 Cyclotron Rd., Bldg. 90, Rm 1116, Berkeley, California 94270. 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