THE SAGUENAY, QUEBEC, EARTHQUAKE LIGHTS OF NOVEMBER 1988-JANUARY 1989
France St-Laurent
Comm. Scol. Marguerite-Bourgeoys, Centre Clement, LaSalle (Quebec),
Canada H8R 1X8 france.st-laurent@csmb.qc.ca
From November 1988 until the end of January 1989 the Saguenay region (Quebec, Canada) experienced 67 earthquakes (EQ). A foreshock M 4.8 mbLg occured on November 23. Two days later, the 25th, an unexpected M 6.5 mbLg shock was recorded (both shocks occured during hours of darkness). All aftershocks were also recorded during the following months of December and January.
Following the same spatial and temporal pattern of the seismic activity, 46 unusual luminosities were seen by some Saguenay and Lac St-Jean inhabitants; of these, 8 preceded the foreshock. Most of the sightings fit the 5 category classification system by Montandon: seismic lightning (mostly, reddish atmospheric glow) luminous bands or rays, globular incandescent masses, fire tongues (small flames creeping near the ground) and seismic "flame" (or flame-like luminosity). The author propose a 6th category: the coronal and point discharge-like type. Most of the reports compare favorably with observations during other large EQs: Longling (China) 1976, Vrancea (Romania) 1940 and 1977, Kobe (Japan) 1995, etc... Of particular interest is one report of a trapper standing near an important fault (Saguenay Graben South wall) and only 17 km from the main shock epicenter, who, while engulfed by a fast moving bright bluish-white light, heard a crackling noise emitted by the trees. The crackling noise accompanied the movement of the luminous body, which was contacting the surface of the ground in his motion. Before the main shock, radio interferences were also heard in the AM band (1420 KHz).
Note: A detailled article has been published on that subject in Vol. 71, Nu. 2, March-April 2000 of the Seismological Research Letters.