A very large flood occurred that would undoubtedly have flooded much of the lower parts of the Lillooet River. A second, tantalizing, explosive eruption may have occurred in northern British Columbia in the Mt. Edziza volcanic field. These are, however, undated and may be hundreds to thousands of years old. The repeat interval for volcanism in Canada cannot be accurately given based on our current level of knowledge. Ash in much lower concentrations is expected more frequently.
Alaskan volcanoes remain the greatest source of volcanic hazards to western Canada.
One to two eruptions are expected every year and many of these are explosive in nature. The prevailing winds in this region and in particular the jet stream, flow most commonly in a southeasterly direction taking ash from the Aleutian Arc to the North American landmass. This airborne ash is extremely hazardous to modern jet aircraft. In Alaska a tragedy in December 1989 was narrowly averted when a 747 jetliner flew into an ash cloud from Mt. Redoubt. This near tragedy has resulted in the formulation in Canada of a means of alerting both aircraft and people on the ground to volcanic hazards.