Preliminary results of the magnetic anomaly survey around Tokara Islands during the GB21-2, GB21-3, and GS21 cruises

DOI Web Site 2 Citations 6 References
  • SATO Taichi
    AIST, Geological Survey of Japan, Research Institute of Geology and Geoinformation
  • KOGE Hiroaki
    AIST, Geological Survey of Japan, Research Institute of Geology and Geoinformation

Bibliographic Information

Other Title
  • GB21‒2，GB21-3 及びGS21 航海（トカラ列島周辺海域）における磁気異常観測の概要

Abstract

<p>Geomagnetic surveys were conducted to make a marine geophysical map in the northern part of the Tokara Islands. A total magnetic anomaly map was made based on the observed total magnetic field. In addition, a magnetic anomaly map of the whole Tokara Islands was made together with the total magnetic anomaly calculated from the vector magnetic surveys obtained in the southern Tokara Islands last fiscal year. Magnetic dipole anomalies are observed around the island arc area and several bathymetric highs, presumed to be due to volcanic activity. Geomagnetic and published gravity features suggest that the north-south trending ridge on the western side of the survey area forms the eastern edge of the Okinawa Trough containing igneous activities. A positive magnetic anomaly is observed in a part of this topographic ridge, which is presumed to be due to magnetization caused by surface volcanic activity or a deep-seated magnetic body. On the trough, a positive magnetic anomaly without seafloor bathymetry is observed. Based on the published regional magnetic map, this anomaly is considered part of a magnetic dipole anomaly, suggesting subseafloor magmatic activity.</p>

Journal

  • BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN

    BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN 74 (5-6), 203-209, 2023-12-28

    National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan

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