Volcanism at the Mount Edziza volcanic complex (MEVC) has been active for the last 11 – 12 Ma in Stikine Country of NW British Columbia.  Over that time, volcanic activity constructed a 75 x 20 km (1,000 km3) steep sided volcanic plateau topped today with the Mount Edziza stratovolcano and caldera, numerous satellite domes and pyroclastic cones.  Over 30 of them were constructed over the last 10 ka.  Some of these are younger than 1,300 years old.  The most recent activity erupted basalts some 1,000 years ago.

The area is glaciated, and much of the activity took place in contact with glacial ice sheets and melt water from those sheets. 

The area is remote, without roads, though there are rivers bounding the plateau.  Smithsonian GVP lists less than 1,000 living within 100 km from the complex.  Much of the complex was designated as a provincial park in 1972.  It was later expanded and surrounded by a larger conservation area.  Recreation is popular, with hiking, mountain climbing, camping, fishing, hunting, hiking and backing popular.  Visitors need to treat a visit here as a backcountry visit, meaning they are for all intents and purposes on their own should an unfortunate incident occur.  Cold and water are among the most unforgiving features of backcountry adventures in the North.  Local natives made use of obsidian found at volcanoes like Edziza in NW British Columbia and traded it as far and wide as Alaska and Alberta. 

Climate here has warm summers and cold, snowy winters.  Edziza itself is snow covered year-round, with a glacial cap.  Average winter temperatures are -7° C, with average summer highs +7° C.  The climate is described as a maritime glacial climate. 

Canadian Volcanologist JG Southern published perhaps the definitive publication on Edziza in 1992, The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia, 320 pp.  This is not an easily found book outside specialized university libraries. 

Volcanoes in Canada are monitored by Volcanoes Canada, part of the Canadian Hazard Information Service under Geological Survey of Canada.  There is no obvious page monitoring Canadian volcanoes in real time like we see out of the various volcano observatories in other nations.  But Canada does have a fully functioning nationwide seismic network (Earthquakes Canada) that should pick up volcanic activity and precursor earthquake activity. 

Region

The Northern Cordilleran Volcanic Province (NCVP), formerly known as the Stikine Volcanic Belt is one of the largest volcanic provinces in North America.  Its 1,200 km long axis is generally parallel with the Pacific Coastline.  Volcanism is confined between the Denali Fault to the W and the Tintina Fault to the E.  The province extends 900 km into E Alaska to the N and 300 km S of the Edziza volcanic complex.  Volcanism in the NCVP is consistent with extensional / rifting tectonics, as the movement along the fault lines on the boundaries is strike – slip.

Over the last 20 Ma, over 100 vents have been active in the province with a variety of eruptive styles.  At least four of these are major stratovolcano complexes active in the last 15 Ma:  Hoodoo Mountain; Mount Edziza volcanic complex; Level Mountain; and Heart Peaks.  There have been at least four tephras identified in the region.  Four of them are tentatively tied to the four major stratovolcano complexes just named.  The fifth is the easternmost distribution of the White River Ash of Mount Churchill in Alaska. 

Level Mountain is the largest of these volcanic complexes covering over 1,800 km2 with a volume of 860 km3.  Mount Edziza is the second largest system covering 1,000 km2 with a volume of 670 km3.  Heart Peaks is next, covering 275 km2 with a volume less than 160 km3.  Hoodoo Mountain has a base diameter of 6 km, an area over 28 km2 and a total volume of just over 17 km3.  There are the remains of an eroded shield covering over 900 km2 in the W Cassiar Mountains known as the Maitland Volcano. 

Level, Hoodoo and Edziza were large enough and high enough to support ice caps that likely altered the movement of regional ice sheets in the past.  Edziza and Level have shelves of older lavas over 1 km up slope and zones of active hydrothermal systems.  These also had an impact on movement of the regional ice sheet in addition to that of their individual ice caps. 

Hot springs are present throughout the NCVP.  The Lakelse Hot Springs are one of the hottest in Canada.  Magma associated with the Nass Valley eruption 250 years ago may be heating the hot springs.  IN our regional review, we will measure distances from Edziza caldera to regional volcanic complexes. 

Tuya Volcanic Field

Tuya Volcanic Field is located some 104 km N of Edziza.  Activity 1.6 Ma – 10 ka was associated with glacial ice sheets, most recently the Cordilleran Ice Sheet.  Oldest volcano ice interaction formed tuyas like Tuya Butte on the Tanzilla Plateau.  Volcanism in the plateau formed multiple tuyas over 100 m high.  Ice thickness during this phase was relatively uniform.

At the same time, activity took place E, S and SW of the Tanzilla Plateau in the Cassiar Mountains, Skeena Mountains and in the Boundary Ranges.  There are few large remnants of volcanic activity here, though there are outcrops of pillow lavas and volcanic breccias found on the summits of sharp, rugged mountain ridges.    

The Cassiar Mountains and Tanzilla Plateau are dominated by tuyas of the Tuya volcanic field.  At least six of these were formed beneath glacial ice close to Tuya Lake.  One of these, Ash Mountain is constructed of pillows and hyaloclastites.  South Tuya is built of loose volcanic debris with basaltic dikes.  Tuya Butte has no summit crater or obvious vent, and is thought to be fissure fed.  The Gabrielse Cone, near the headwaters of Iverson Creek is the youngest cone in the field. 

Heart Peaks

Heart Peaks is located just W of Level Mountain, 125 km NW from Edziza.  It tops out 2,012 m.  It is a basaltic and trachybasaltic shield built with layered lavas and pyroclastics.  The stratovolcano is topped with rhyolitic domes.  The oval shield measures 33 x 19 km at its base.  The E and W flanks are heavily eroded.  The N flank is rounded and the S flank is pointed.  The highest point is a small peak in the middle of the summit plateau.  More than 20 unnamed creeks drain the plateau into nearby rivers.

Little is known about the eruptive history of Heart Peaks as it has not been studied in any detail.  Initial activity is thought to begin 23 – 2.5 Ma.  It initially produced effusive basalt eruptions followed by more explosive silica rich trachytes and rhyolites.  There are phreatic breccias indicating eruptions taking place in contact with ice and water.  Activity since 2.5 Ma is unknown. 

Heart Peaks is one of four volcanoes in the NCVP suggested to have erupted the Finlay tephras, which cover much of N British Columbia and stretch into the Canadian Rockies.  These tephras are most chemically similar to those from Mount Hoodoo.  

Level Mountain

The Level Mountain shield is a massive volcano covering 1,800 km2 88 km NNW from Edziza.  It has a volume of over 860 km3, topping out at 2,164 m.  The lower half of the mountain is a massive basaltic shield 70 x 45 km, with an average 750 m thickness.  Volcanism erupted pahoehoe over blocky a’a flows, breccias and tuffs.  Glacial ice and streams have eroded the plateau into valleys and ridges forming the Level Mountain Range on the central summit of Level Mountain.  It is capped with more recent silicic domes.  There are more than 20 recent eruptive centers on the central portion of the volcano and its flanks. 

Initial activity began 15 Ma with eruption of voluminous lava flows building a large shield.  A second stage starting 7.1 Ma built a stratovolcano on top of the shield.  This was a bimodal system with effusive lavas and explosive silica eruptions.  Much of the original volcano was constructed before glaciation.  There are breaks in activity up to 1 Ma during which glacial erosion has been active on the mountain.  Much of its later activity took place in contact with glaciers and regional ice sheets.  Glaciers eroded much of the stratovolcano leaving a series of U-shaped valleys on the top of the shield, the Level Mountains. 

A third stage extruded domes starting 4.5 Ma.  The most recent stage started 2.5 Ma and continued through the present.  It erupted lava flows and small cones.  Level had many types of eruptions over its eruptive history.  Like neighboring Heart Peaks, Level Mountain has been suggested as the source of the regional Finlay Tephras. 

Castle Rock

Castle Rock is an eroded volcanic plug some 30 km NE from Edziza, 13 km W from Iskut.  It is one of 10 Canadian volcanoes with recent seismic activity.  Castle Rock is one of at least six vents on the Klastline Plateau.  These vents produced subglacial piles of pillow lavas and tuff breccias.  Rocks here date 5.4 – 4.6 Ma, around the same time as activity at Maitland. 

Maitland Volcano

Maitland volcano is a heavily eroded, extinct shield located in the W Cassiar Mountains., some 66 km SE from Edziza.  Like its neighbors, it is a heavily eroded shield topped with a younger volcano.  There is little remaining of the original structure that has not been significantly eroded.  The original structure measures 50 x 40 km and is thought to be 900 – 1,000 km2. 

Activity here began around the same time as neighboring Edziza, though a much shorter time span 5.2 – 4.6 Ma.  Initial activity built a basaltic shield.  Later activity erupted trachytes through the center of the shield.  The volcano went extinct 4.6 Ma.

Prolonged glacial erosion destroyed the shield after it stopped erupting.  Its basement was soft sedimentary rocks which are more prone to erosion.  Remnants of lava flows are present as scattered caps on higher mountains in the range.  Some of these are up to 400 m thick containing up to 20 separate lava flow units.  There is a cluster of 14 volcanic plugs that were originally part of the central volcano.  These are feeders that Maitland lavas reached the surface. 

Hoodoo Mountain

Hoodoo Mountain, 111 km SSW from Edziza is a massive volcanic structure that tops out at 1,850 m.  Activity here began 100 ka, mostly under glacial ice of the Cordilleran Ice Sheet.  More than 90% of the volcano was formed under glacial ice.  It has interlayered lavas and hyaloclastites.  The volcano is glaciated, surrounded by glaciers on three sides, with the S side being uncovered.  All flank lava flows were erupted under ice.  There was at least one explosive eruption that produced welded and unwelded ignimbrite on the N side of the volcano. The Finlay Tephras.

Little Bear Mountain is a recent tuya on the N flank of Hoodoo Mountain.  Lava flows with well-preserved channels on its NW and SW flanks show no interaction with ice.  Estimates of these most recent lava flows range 7 – 1 ka.  There have been at least 8 seismic events here since 1985. 

While the Wiki lists Hoodoo as one of the Iskut – Unuk River Cones, everything else I’ve come across deals with it as a separate system.  Hoodoo is one of the largest volcanoes in the NCVP.  It is a stratovolcano formed by layered basalt, trachyte lava flows and hyaloclastites.  The pile of volcanic rock that has interacted with ice is up to 2 km thick.  It has a nearly flat summit.  Lava flows from the main volcano have mostly buried Little Bear Mountain, an older and smaller basaltic volcano immediately N.  Hoodoo is just over 17 km3 in volume, standing 900 m above the surrounding valley. 

The volcano was built in at least six eruptive periods over the last 85 ka.  Three of these involved ice.  Three did not.  There are several tephra layers in the region that are thought to be erupted from to Hoodoo.

The initial eruptive period produced massive subglacial lava flows and hyaloclastite breccias.  These layers are 500 – 1,000 m thick.  It is unclear whether these eruptions completely melted overlying ice.  The area was glaciated several times before the start of volcanic activity.  The second period erupted from the summit which at that time was above the ice 80 ka.  Lava traveled a distance downslope and ponded against thick glacial ice at 700 m.  The ponded lavas created a set of cliffs around the base of the volcano.  The cliffs here are 30 – 200 m and often have columnar joints. 

After ice withdrew at lower elevations, explosive activity 80 – 54 ka in the third period created pyroclastic flows on the N flank up to 100 m thick.  The sequence has layers of unwelded lapilli tuff, ash, and three highly welded layers up to 5 m thick.  Lava flows traveled down the N and NE flanks at the end of this period.  The fourth period 54 ka was effusive, stacking lava flows on the N and SW flanks 10 – 30 m thick.  These did not interact with ice, meaning the upper flanks were ice free at the time of eruption.  Some of these are jointed.

Subglacial eruptions resumed 54 – 30 ka in the fifth period.  Overriding ice 54 – 40 ka may have been up to 2 km thick.  Subglacial eruptions of lavas, breccias and hyaloclastites formed a 400 m thick volcanic unit.  The second part of this period 40 – 30 ka was fissure fed eruptions beneath a relatively thin ice cover.  These erupted a 30 – 50 m thick series of lava flows, lobes and breccias on the N, NW and W flanks of Hoodoo.

The most recent eruptive period 10 – 9 ka erupted 5 – 10 m thick lava flows from the summit down the N, NW, SE and SW flanks.  None of these encountered ice.  Regional ice had disappeared at lower elevations.  Flows traveled up to 3 km downslope, partly covering the cliffs at the base of the volcano.  Dating of these flows is variable, between 10 ka and 180 years ago.  They have not been eroded, which tends to support the conclusion they are very recent. 

Iskut

The Iskut – Unuk River Cones, 128 km S of Mount Edziza, built a smallish volcanic field with eight small volcanoes.  Once again, dating of activity here is widely variable.  Lava flows date 70 ka, while the cones date 9 ka to a few hundred years ago.  At least five of these cones sent lavas 20 km down the Iskut and Unuk River valleys.  The other three volcanoes formed in contact with ice, creating scoria, pillows and hyaloclastites.  The most recent eruption took place at Lava Fork volcano in 1800, the most recent eruption in Canada.  There is a possible eruption in 1904 attributed to the Lava Fork cone. 

Mount Edziza Volcano

The Mount Edziza Volcanic Complex is the second largest volcanic complex in the region, covering over 1,000 km2.  It has a volume of 670 km3.  There are three main stratovolcanoes associated with the volcanic complex:  Armadillo Peak; Spectrum Range; Ice Peak; and Mount Edziza.  Activity at Edziza may date as far back as 12 Ma.  Cycles start out effusive erupting basalts and evolving into more felsic (trachyte) magmas.

Early activity built Armadillo Peak, the oldest and most central of four central volcanoes in the complex.  It is topped by 180 m thick trachyte lavas that ponded in a caldera forming a lava lake 6 Ma during its final active stage. 

The Spectrum Range part of the Edziza volcanic complex is located at the S end of the complex.  It was constructed 3.0 – 2.5 Ma.  It is a nearly circular dome is up to 650 m thick and more than 10 km wide build on a basaltic shield.  The dome has been deeply eroded forming an extensive valley system which in turn exposes large lava flows of the dome including a 4.5 km wide caldera in the shield. 

Ice Peak overlaps the N flank of Armadillo Peak.  Eruptions creating it started as the regional Cordilleran Ice Sheet started retreating from the Mount Edziza complex 1.6 Ma.  It is a stratovolcano constructed when large areas of Edziza were mostly ice free, though there was enough ice remaining for its lavas to interact with.  Initial activity produced lava flows on the flanks forming meltwater lakes.  Pyroclastics mixed with meltwater to form debris flows. 

Mount Edziza is a steep stratovolcano overlapping the N flank of Ice Peak.  It is the most N of four central volcanoes in the complex, forming some 1.0 Ma.  It has smooth N and W flanks and is topped with a 2 km diameter ice-filled caldera.  Active cirques breached the E caldera rim, exposing remains of several lava lakes that ponded in the caldera 900 ka.  Subglacial eruptions on the flanks of Edziza and Ice Peak produced piles of pillows and hyaloclastites. 

Edziza Magmatic Cycles

The first magmatic cycle took place 12 – 5.3 Ma, creating the Raspberry, Little Iskut and Armadillo Formations.  Raspberry began erupting 83 km3 of basalts building a massive shield.  Lava flows were over 300 m thick at the source, a few meters thick at their ends.  Lavas dammed local drainages creating Raspberry Lake in the upper Little Iskut River valley.  Lavas were initially erupted from the core of the system, later migrating to satellite cones on its flanks.  The initial shield covered at least 775 km2 and was nearly 2,100 m high.  Little Iskut eruptive period started 7.2 Ma centered beneath the waters of Raspberry Lake.  Interaction between the magma and lake water was phreatic with multiple violent explosions and ash emissions.  Later eruptions created a dome that eventually formed a small volcanic island.  This dome grew to a broad shield that displaced much of the water of the lake with lavas and volcanic debris from the phreatic activity. 

The Armadillo period took place 7.0 – 6.0 Ma.  It began explosively from a vent near Cartoon Ridge, producing 10 km long pyroclastic flows and ashfall covering several hundred km2.  This was followed by effusion of trachytes and rhyolites creating overlapping domes.  Rapid evacuation of a shallow magma chamber created the 3 km diameter Armadillo caldera.  Lavas filled the caldera floor creating a lava lake.  Lavas spilled outside the caldera, forming a 13 km long sequence of flows to the W up to 460 m thick.  There were a number of volcanic centers active during Armadillo.  All erupted trachytes and rhyolites. 

The second magmatic cycle took place 6.0 – 1.0 Ma.  Like Armadillo, it is subdivided into three parts, Nido, Spectrum and Pyramid.  Like the first cycle, it started out effusively and evolved to trachytes and more explosive eruptions.  The Nido Formation activity took place 6.0 – 4.0 Ma.  It erupted highly mobile basalts from at least six major volcanoes.  The oldest of these have been highly eroded.  Spectrum took place 4.0 – 2.0 Ma.  It began with a small explosive eruption of pumice and ash and quickly evolved into effusion of massive rhyolite lava flows.  These changed to trachytes as the deeper part of the magma chambers were tapped building a dome.  As the chamber was evacuated, it collapsed, creating the 4.5 km diameter Spectrum caldera.  This caldera was eventually buried by lavas from subsequent eruptions.  Note that both caldera formation events are described as collapse events rather than explosive events. 

The Pyramid eruptive period took place around 1.1 Ma.  Initial activity was explosive trachyte eruptions from a vent on the NW margin of the complex.  It was accompanied by phreatic explosions and pyroclastic surges.  A short period of later eruptions sent thin basalt flows into a neighboring valley N of the complex, forming a small lava-dammed lake.  This was followed by much more viscous flows and extrusion of domes forming The Pyramid.   After a period of quiet, the Sphinx dome extruded under ice.  It grew to 800 m high and 5 km long.  The final pulse built Pharoh Dome.  Initial activity was subglacial with phreatic explosions.  As the dome grew above the top of the ice, continued rhyolite extrusion enlarged the dome.

The third magmatic cycle built Ice Peak, Pillow Ridge and the Edziza stratovolcano.  This activity dates 1.6 – 0.9 Ma.  Ice Peak eruptions started when the complex was covered by a receding regional ice sheet.  Activity began on the S flank of Sphinx Dome where pyroclastics mixed with meltwater to create debris flows and lahars.  Lava flows crossed the glaciers as successive eruptions built Ice Peak.  Basaltic flows downslope were followed by trachytes around the summit, building a steep symmetrical stratovolcano.  Its structure was destroyed by glacial erosion.  Activity extruded an unusually thick lava flow with two lobes and built a few subglacial volcanic vents.  Activity at Pillow Ridge started 0.9 Ma with a subglacial eruption of basalt that eventually created a meltwater lake inside the glacier.  The volcanic pile left by these eruptions is called Pillow Ridge. 

Activity leading to Edziza started on the N flank of Ice Peak after the regional ice sheet had retreated.  It built a symmetrical trachyte stratovolcano.  The original cone collapsed, forming a 2 km diameter caldera.  Subsequent eruptions created domes and a lava lake inside the caldera and a few vents on the lower flanks.  The volcano was at least 610 m higher before the collapse than it is today. 

The fourth magmatic cycle took place 0.8 – 0.2 Ma.  Like the other cycles, this one is also divided into three periods, Arctic Lake, Klastline and Kakiddi.  The oldest of these, Arctic Lake, built at least 7 basaltic volcanoes.  Lava from these interacted with ice and meltwater in varying degrees.  Klastline activity took place 0.6 Ma.  Initial activity erupted massive basalt flows along the N flank of Edziza.  One of these was 25 km long.  Pyroclastic cones also erupted lavas during this phase.  The final eruptive period, Kakiddi, was active 0.3 ma.  It erupted a massive trachyte flow down the E flank which eventually covered over 20 km2.  The source of this flow is unknown but may have been Ice Peak or the Nanook Dome at the summit of Edziza. 

Recent Edziza Eruptions

There have been more than 20 eruptions at Mount Edziza in the last 10 ka.  At least two of these are no more than 1,300 years old based on plants buried under loose basaltic fragments.  The Snowshoe Lava Field is one of the youngest lava flows in the region.  The largest of these flows cover over 150 km2.  The longest is 12 km.  Volcanic activity was followed by at least two younger, but as yet undated eruptions. 

The most recent eruptive cycle, Edziza’s fifth, has been active over the last 20 ka.  The Big Raven cycle erupted subglacial volcanoes, cinder cones, lava flows along the length of the complex.  There was a VEI 3 pumice eruption from the SW flank of Ice Peak.  Most of the activity took place on the W flank of Ice Peak and the N flank of Edziza.  Lava flows there formed the Desolation and Snowshoe lava fields.  Most of the eruptions were basaltic, though there were some trachytes.

Initial activity at the Snowshoe Lava Field during Big Raven took place high on the W flank of Ice Peak, where basalts erupted under the ice cap, forming a pile of pillow lavas that formed Tennena Cone.  Lavas reached the W edge of the ice cap and interacted explosively with meltwater.  There are another pair of subglacial cones S of Tennena Cone.  As the ice retreated, continued activity built multiple other cones via lava fountaining.  Massive lava flows spread into neighboring creek valleys.  At least one of these was from a fissure eruption forming The Saucer, one of the youngest features in the Snowshoe Lava Field. 

Continued activity created Nahta Cone near the N edge of Arctic Lake Plateau and at least one destroyed cinder cone on the S flank of Kuno Peak.  Kuno Peak partly collapsed, removing the new cone and burying its lava flows.  There are three eruptive centers on the E flank of Mount Edziza.  Cinder Cliff ponded lavas against ice.  Two other centers were glaciated and poorly exposed.  Both of these produced lava flows that are mostly buried under glacial debris and ice.  One lava flow stretches 6.5 km along a valley on the E slope of Mount Edziza. 

The Desolation Lava Field built at least 10 cinder cones.  Lavas from this field covered glacial till.  One of the flow sequences is at least 12 km long.  Another is 14 km long.  These flows temporarily dammed streams in the valleys they flowed down.  Most recent activity dates some 1,400 years ago,

The Mess Lake Lava Field is located NW of Spectrum Range.  It has three cinder cones.  Lavas from these flowed across a scarp and into the neighboring creek valley.  Most of these were removed by glacial erosion.  Ash Pit produced pyroclastics that were blown NE by a strong, uniform wind during its eruption.  Kana Cone erupted basalt lavas down the neighboring Klastline River valley, also damming the river in places. 

The VEI 3 eruption took place from the SW flank of Ice Peak near the end of Big Raven.  Its pyroclastic fall covered at least 40 km2, everything in the Snowshoe Lava Field other than The Saucer which erupted afterwards.  This pumice dates around 1,000 years ago, though there is a wide error bar associated with this date.

Finally, while the complex is volcanically dormant, it is hydrothermally active.  There are at least four hot spring areas along its W flank.  Most of these are powered by water interaction with magma.  One if thought to discharge from a deep circulating hydrothermal system bounded by a local fault.  Water temperature and water volume available give it potential for high temperature geothermal exploration.  This has not yet been done due to its remote location.

Tectonics

Bedrock under the NCVP consists of four terranes added to North America as far back as the Mesozoic.  Subduction ended here at least 40 Ma.  Over the last 10 Ma, tectonic activity has shifted to extension / rifting between the two boundary faults.  There is some argument about precisely what is going on, though volcanic rocks erupted since then are typical of extensional / rifting tectonics.  The S boundary of the province parallels the N boundary of the Cascadia Subduction Zone, with little to no volcanism in the N part of that gap.  Plate is as thin as 18 km in places in the S portion of the NCVP thickening to nearly 40 km. 

Movement along the Tintina Fault to the E over the last 35 Ma is offset at least 450 km, though there is some evidence that offset may be as much as 1,200 km.  Movement along the Denali Fault to the W over that time is at least 370 km. 

Activity in the province has declined over the last few Ma though there have been two pulses over the last 8 Ma.  Activity 8 – 4 Ma was higher than today with magma production 8 – 7 Ma related to rifting along the Pacific and North America Plate boundary.  There was a pause in activity 4 – 3 Ma.  The most recent active phase 2 Ma – present constructed 25 volcanic zones, producing over 100 km3 of material, though at a lower rate than the earlier pulse.  The initial phase produced 250 km3 of material.  Current activity in the province is much lower than that of the Cascades or Hawaii.  The caution to this conclusion is that volcanic products erupted before the last glaciation have been eroded by the regional ice sheets.  Much of that erosion debris has not been dated in sufficient detail to identify local or regional vents.  

Conclusions

The Mount Edziza Volcanic Complex is a huge, recently active volcanic system.  It and most of its neighbors have been recently active, with basalts rather than more evolved magmas erupted.  There are multiple active hydrothermal systems that have altered rocks to the extent that gold mining is being explored.  Happily, most of the systems are remote, though the most recent eruption in the province (Tesax in the far S end) was deadly to the local native population.  Given the ongoing extension, future eruptions should not be a surprise. 

Additional information

147.  Mount Edziza (1992), The History of the Geologizal Survey of Canada in 175 Objects, Government of Canada

Crystal fractionation of the basalt comendite series of the mount Edziza volcanic complex, British Columbia:  Major and trace elements, Southern & Hickson, Jun 1984

4.6 Volcanoes in British Columbia, Physical Geology, BC Campus 

Mount Edziza volcanic complex, Place and See

Evolution of a subglacial basaltic lava flow field:  Tennena volcanic center, Mount Edziza volcanic complex, British Columbia, Canada, Hungerford, et al, Feb 2014 

Recognizing ice-contact trachyte-phonolite lavas at the Mount Edziza volcanic complex, British Columbia, Canada, K LaMoreaux, 2008

Subglacial, phonolitic volcanism at Hoodoo Mountain volcano, northern Canadian cordillera, Edwards, et al, May 2002

A record of early Pleistocene glaciation on the Mount Edziza plateau, northwestern British Columbia, Spooner, et al, Dec 1995

Reassessing the role of Mount Edziza obsidian in northwestern North America, R Reimer, Jun 2015

Distribution, nature and origin of Neogene – Quaternary magmatism in the northern Cordilleran volcanic province, Canada, Edwards & Russell, Aug 2000

Aenigmatite from Mt. Edziza, British Columbia, Canada, Yagi & Southern, 1974

Evaluation of mineral potential for Mount Edziza recreation area, P Wojdak, Sept 1993

Geology, U-Pb geochronology, and geochemisty of the Miocene Pheno Mountain complex, Hoodoo Mountain area, British Columbia, Zagorevski, et al, 2012

The vulnerability of Canada to volcanic hazards, Hickson & Mulder, 2003

Holocene tephras in lake cores from northern British Columbia, Canada, Clague, et al, Aug 2008