Resolution No.3 (1973): SI Units

IAGA, considering that SI Units are achieving international recognition as a single standard for worldwide use, recommends adoption of SI Units in the field of geomagnetism. Specifically IAGA recommends that:

    1. Values of the geomagnetic "field" be expressed in terms of the magnetic induction B (SI Unit tesla=Weber/meter [squared])
    2. If it is desired to express values in gamma, a note should be added stating that "one gamma is equal to one nanotesla".
    1. Values of "intensity of magnetisation" be expressed in terms of magnetisation M (SI Unit Ampere/meter).
    2. If it is desired to express values in e.m.u., a note should be added stating that "one e.m.u. is equal to 1000 ampere/meter".
    1. Values of susceptibility be expressed as a ratio between magnetisation M and the magnetic field H.
    2. If, during the transitional period, it is desired to use values of susceptibility in e.m.u., a note should be added stating that "[chi] SI is equal to 4 [pi] [chi] e.m.u.".