Memoirs of the Kakioka Magnetic Observatory Vol.13 No.02， p.31, March, 1970

Results of Magnetic Survey in the Kakioka Magnetic Observatory ground in 1968

Ochi, K.

Abstract

 In this paper，the author reports some results of accurate and detailed magnetic survey which was carried out at the “Hibariga Oka" hill in the Kakioka Magnetic Observatory ground in 1968.
  On the hill new standard magnetometer house will be built in near future. Some magnetic anomalies have been found by this survey.
  Those anomalies are due to the topography of the hill or to the building and equipment of the observatory.
  At the middle part of the hill，the surface of the ground is nearly flat，nevertheless，magnetic field gradient deduced from the equal lines of magnetic force is not so small.
  The gradient of total magnetic force is about 1O-20γ/1O m there.
  It may be an effect of the topography of the hill shirt and the building or equipment near the hill.
  Before the construction of new standard magnetometer house on the hill，it is desirable to level the ground and to remove the building on and near the hill.
  ln the construction of a house，the magnetic effect made by the removal of soil for foundation works may be unexpectedly large sometimes.
  Then it is necessary to diminish the effect by careful consideration.

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