Edziza Volcano - John Seach

john

British Columbia, Canada

57.72 N, 130.63 W
summit elevation 2786 m
Stratovolcano

Mount Ediziza Volcano is located in NW British Columbia. It lies east of the Coast Crystalline Complex and along a zone of north-south normal
faults.

Mount Edziza contains a central summit crater 1.6 km in diameter. The volcano contains lava domes, pyroclastic cones and a 2 km wide ice-filled caldera.

Lava at Mt Edizza volcano was erupted in three stages.

Stage 1. The initial eruption produced thin fluid basalt flows which erupted from several separate central vents and coalesced to form the basal shield of the Edziza complex. The basal shield and lava domes were deeply eroded before the beginning of stage 2.

Stage 2. The first lavas of stage 2 lavas erupted from at least four separate central vents along the north-south axis of the older shield. The lavas consisted of alkaline basalts that formed mobile flows which spread in thin sheets over most of the old plateau surface. Activity then shifted to the main crater of Mount Edziza. Stage 2 culminated with a small explosive eruption of trachytic pumice, followed by eruption of a large volume of trachyte lava flows. The eastern rim of Mount Edziza stratovolcano was destroyed by phreatic explosions and deeply eroded before the onset of stage 3.

Stage 3. Stage 3 began with the eruption alkaline basalt from a satellite vent on the north flank of the main stage 2 cone. This was followed rapidly by eruption of basalt from over thirty separate vents on the flanks of the main stratovolcano. Stage 3 culminated with the explosive discharge of rhyolitic pumice from a vent, now covered by glacier ice, on the southern flank of the main cone of Mount Edziza. This pumice is free of vegetation and covers an area of 77 sq km, and has a depth of 1.5 m.

Edziza Volcano Eruptions

Approx 1000-3000 years ago.