Report on DELP 1986 Cruise in the Northwestern Pacific : Part 4: Measurement of Three Components and Total Force of the Geomagnetic Field

During the DELP-1986 cruise, three components of the geomagnetic field and the total force intensity were measured with an STCM (Shipboard Three Component Magnetometer) and a proton precession magnetometer. STCM provides three component geomagnetic field intensities on board a research vessel, of which results can be used to identify the orientation of the magnetic lineament from only one single ship track. Our data give some additional information on the magnetic anomaly lineation patterns of the northwestern Pacific and the direction of lineation of the area surveyed by the present cruise is reexamined by the three component magnetic field data. The direction of geomagnetic anomaly lineation of this area is confirmed to run with a N70°E strike. Two vessels were used for the present study, i.e. WakashioMaru for three component magnetometer run and Daisan KaikoMaru for single proton magnetometer run.1986年度夏期に実施されたDELP並びに地震予知共同観測で得られた,地磁気三成分(水平二成分,鉛直一成分)及び全磁力の異常分布について報告する.三成分の測定は船舶用フラックスゲート磁力計により,全磁力は,プロトン型磁力計により行われ,両者間では補正を行なうことが可能である.また三成分磁力計はジャイロによる方位の測定と船体磁気の補正により,地理方位三成分の値として得られる.三成分の利点は,航跡が単数であっても,海底下に分布する地磁気異常源の走向を推定できることにある.今日までに得られている,標題海域の地磁気異常分布について今回の様な測定により,新たな吟味を加える事が可能である.この海域に於ける地磁気異常の走向はN70°Eであることが確認された