The Canadian Geophysical Union (CGU) had a very successful joint meeting with the Canadian Meteorological and Oceanographic Society (CMOS) at Dalhousie University in Halifax, Nova Scotia, May 29 to June 1, 1984. Thirty-five scientific sessions were held in the 4-day meeting period.
The invited speaker for CGU at the plenary session, David Simpson of Lamont-Doherty Geological Observatory, spoke about the Halifax Explosion of 1917 in terms of a seismic event. The 2.6-kt explosion was the largest man-made explosion prior to the detonation of the first atomic bombs. The effective seismic magnitude of the event may have been m, = 2.5–3.0.