抄録
In order to know precise geomagnetic anomalies in total force at Sagami Bay wherethe large Kanto Earthquake occurred in 1923, magnetic survey was carried out by useof towing proton-precession magnetometers.The effect of magnetization of the ship was removed by use of a pair of magnetometerstowed 50 m and 200 m apart from stern of the ship. Ship's position wasdetermined by use of Loran C within an accuracy of 50 m. Magnetic daily variationwas removed by use of data given from the ocean bottom magnetometer deployed atthe same region.By repeating the observation, it would be possible to detect variation of local geomagneticanomalies due to earthquakes or volcanic activity.
