Resolution No.9 (1977): Continuity of secular change record at a change of geomagnetic observatory

IAGA, considering that determining secular change and other magnetic parameters needs long-term operation of magnetic observatories but may require the movement of an observatory to a new site because of artificial disturbances, recommends that

1. repeat stations be set up near each observatory to preserve the secular change record in the event of a change of the observatory base reference,
2. when it becomes obvious that an observatory should be moved, plans be made to operate instruments simultaneously at the old and the new sites for a period of at least one year.