Volcanic Hazards in Canada - A Review
Catherine J. Hickson (Geological Survey of Canada, 101-605 Robson Street,
Vancouver, British Columbia)
Canada’s western margin is tectonically active, and though little known to most Canadians, contains numerous
volcanoes. Separated into four belts (Souther, 1977) and one volcanic field (Hickson et al., 1995) (Figure 1)
the volcanoes are the result of differing tectonic origins. The Garibaldi and Wrangell belts are subduction
related, and the Anahim belt is associated with a mantle hotspot (Souther, 1986; Hickson, 1987). The Stikine
(or the northern Cordilleran volcanic province of Edwards and Russell, in press) appears to be related to
crustal rifting (Souther, 1977, 1990; Edwards and Russell, in press), and the Wells Gray-Clearwater Volcanic
field to crustal weaknesses along the intersection between the Intermontane and Omineca geomorphological
belts (Gabrielse and Yorath, 1991), where thinning crust and crustal penetrating structures may account for
the alkali-olivine basalt magmatism seen in this region (Hickson, 1987; Hickson et. al., 1995).
Figure 1: Schematic representation of the
volcanic belts and fields of the Canadian
Cordillera.
AL
AS
KA
Mount
Churchill
Volcano Mountain
14
0
60
Legend
Late Miocene-Pliocene complexes
Large volcanic complexes
Alligator
Lake
Cinder cone/small shield volcano
Chilcotin basalt
Neogene Chilcotin basalt
SU
BD
UC
YUK
ON T
ERR
ITOR
Y
T IO
N
Heart
Peak
ZO
120
N.W.T
.
Tuya Butte Volcanic Field
N
E
Level Mountain
60
Mount Edgecumbe
Stikine River Volcanic Field
Edziza Volcanic Field
56
IA
COLUMB
BRITISH
The Thumb
ALBERT
A
F O R M FA U LT
TTE TRA NS
Pacific Plate
Iskut-Unuk River Cones
Tseax River Cone
North American Plate
Maitland Volcanics
Hoodoo Mountain
136
The most recently active of these volcanic belts
has been the Stikine. Within this belt there have
been two reported, but unsubstantiated, eruptions
in the late 1800’s and several eruptions known
to have occurred in the last 400 years (Hickson,
1990). Of these the youngest appears to be the
eruption of a small cinder cone called Lava Fork
in the Iskut-Unuk River cones (Figure 1; Russell
and Hauksdottir, in press).
QUEEN
C HARLO
Most of the recent volcanism in the Stikine belt
is basaltic in nature. The low viscosity lavas have
traveled distances of several tens of kilometers.
52
Ash fall from these centres is unknown but would
132
be expected to be very localized. The greatest
hazard from eruptions such as those seen in the
very recent past is from damming of the rivers
by lava flows. These lava dams generally tend
to be unstable, failing without warning, or
200
rerouting the water course in unpredictable ways.
km
Significant sediments are generated that would
have a very deleterious effect on fish, especially
if the eruption occurred during spawning. If the
eruption were to occur in the wintertime, some flooding would also be expected due to rapid melting of
snow. Ash fall would be limited, but might create localized problems if the eruption occurred in areas of
active logging. These hazards, though, would have a relatively low impact on people, as the volcanoes tend
to be in remote areas and, with the exception of flooding or disruption of the waterway, are fairly localized.
Ilgachuz
Range
Milbanke
Sound
Cones
Rainbow
Range
Itcha
Mtn.
Nazko
Cone
Silverthrone
Franklin Glacier
Bridge River
Cones
Mount Meager
"Explorer
Plate"
Mount Cayley
S
U
BD
UC
Mount
Garibaldi
T IO
N
ZON E
Juan de Fuca
Mount Baker
Plate
U.S.A.
Explosive volcanism is not unknown in western Canada, but there is only one well-documented case. This
is the 2350 B.P. eruption of Mount Meager in southwestern British Columbia (Figure 1). The eruption
Volcanic Hazards in Canada - A Review (C.J. Hickson)
created significant hazards in the region (Hickson et al., 1999) and is a model for the problems faced when
eruptions occur in areas of extreme topographic relief (Hickson, 1994). A very large flood occurred that
would undoubtedly have flooded much of the lower parts of the Lillooet River. Ash can be found over 700
km to the east, indicating that the eruption was very vigorous and deadly; the column height is estimated at
least 20 km (Hickson, et al., 1999). A second, tantalizing, explosive eruption may have occurred in northern
British Columbia in the Mt. Edziza volcanic field (Figure 1). Thick pumice deposits are reported on the
glaciers and over a wide area to the south of Mount Edziza (Souther, 1992). 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. However, a crude review of known eruptions would suggest that eruptions occur on the order of
2 – 3 times a century, but these would most likely be basaltic eruptions, relatively benign in nature. Is there
then any need to develop plans for the eventuality of an eruption? The answer is yes, for although volcanoes
in Canada are only infrequently active, those to the south (Washington to northern California, U.S.A.) and
north (Alaska), have a far more frequent eruption record.
Ash is expected to fall in concentrations large enough to cause problems on the ground in southern Canada
at least once every 1000 years (Hoblitt et al, 1987) and in fact ash from the 1980 eruption of Mt. St. Helens
fell on southern BC, Alberta and Saskatchewan. Ash in much lower concentrations is expected more frequently.
Mt. Baker remains the most problematic of these volcanoes, due to its close proximity to the Canadian
border (20 km) and to the large metropolitan area of Vancouver (80 km east). On the Canadian side of the
border, ashfall and floods are the most likely hazards expected from an eruption of Mount Baker (Hickson,
1994).
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 (Figure 2). 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. The aircraft landed safely on the ground, but suffered over $80 million dollars (U.S.) in
damage. 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.
Figure 2: Composite satellite radar image of the ash plume from
the September 17, 1992 eruption of Mt. Spurr in Alaska (courtesy
of D. Snyder, U.S.G.S.). The satellite radar tracked the plume
all the way across Canada to Greenland. Air traffic was rerouted
around the plume and ash fell in western Yukon, closing the
Alaska Highway for several hours.
In 1990 Natural Resources Canada, Environment Canada,
Transport Canada, RCMP, British Columbia Emergency
Program and Emergency Preparedness Canada met together to
formulate a plan. The document, called the “Interagency
Volcanic Event Notification Plan” or IVENP for short, is a
coordination plan involving all concerned agencies, though in
the short term the most important facet of the plan is warnings
for aircraft. Environment Canada now maintains a permanent
web site, www.cmc.ec.gc.ca/cmc/CMOE/vaac/A-vaac.html
Volcanic Hazards in Canada - A Review (C.J. Hickson)
where plume trajectories are posted on a regular basis for volcanoes in North America as well as other parts
of the world. Environment Canada is also now a designated Volcano Alert Advisory Centre (VAAC), under
the International Civil Aviation organization (ICAO) and as such are responsible for issuing volcanic ash
warnings to airmen over the airspace extending from Greenland to Alaska. Through IVENP and the VAAC,
Canadians are well protected from airborne volcanic hazards. The GSC has also just created a new website,
www.nrcan.gc.ca/gsc/pacific/vancouver where a large range of information on volcanoes and volcanic hazards
in Canada can be found.
Edwards, B.R., and Russell, J.K. in press. Distribution, nature and origin of Neogene-Quaternary magmatism
in the Northern Cordilleran Volcanic Province, Canada, Geological Society of America Bulletin.
Edwards, B.R., and Hickson, C.J. in press. Volcano Atlas, Geological Survey of Canada Bulletin.
Gabrielse, H. and Yorath, C.J. 1991. Introduction, Chapter 1 in Geology of the Cordilleran Orogen in Canada,
H. Gabrielse and C.J. Yorath (ed.); GSC, Geology of Canada, no. 4, p. 3-11.
Hickson, C.J. 1987 Quaternary volcanism in the Wells Gray-Clearwater area, east central British Columbia;
unpublished Ph.D. Thesis, University of British Columbia, 357 p.
Hickson, C.J. 1990. Canadian Cordillera: volcano vent map and table. in Volcanoes of North America, C.
Wood and J. Kienle (ed.), Cambridge University Press, New York, p. 116-117.
Hickson, C.J. 1994. Character of volcanism, volcanic hazards, and risk, northern end of the Cascade magmatic
arc, in Geology and Geological Hazards of the Vancouver Region, Southwestern British Columbia,
(ed.) J.W.H. Monger; Geological Survey of Canada Bulletin 481, p. 231-250.
Hickson, C.J. and Edwards, B.R. in press. Volcanic hazards. Canadian Hazards Atlas, Geological Survey of
Canada Bulletin.
Hickson, C.J., Moore, J.G., Calk, L., and Metcalfe, P. 1995. Intraglacial Volcanism in the Wells GrayClearwater Volcanic Field, East Central British Columbia, Canadian Journal of Earth Sciences, v.
32, p. 838-851.
Hickson, C.J., Russell, J.K., and Stasiuk, M.V. 1999. Volcanology of the 2350 B.P. eruption of Mount
Meager volcanic complex, British Columbia, Canada: Implications for hazards from eruptions in
topographically complex terrain, Bulletin of Volcanology, v. 60, p. 489-507.
Hoblitt, R.P., Miller, C.D., and Scott, W.E. 1987. Volcanic hazards with regard to siting nuclear power plants
in the Pacific northwest, United States Geological Survey, Open File Report 97-297, 196 p.
Moore, J.G., Hickson, C.J., and Calk, L. 1995. Tholeiitic-alkalic transition at subglacial volcanoes, Tuya
region, B.C., Canada, Journal of Geophysical Research, v. 100, p. 24,577 - 24,592.
Russell, J.K. and Hauksdottir, S. in press. Petrology of the Iskut-Unuk river basalts: insights to assimilation
in the northern Cordillera, British Columbia, Canadian Mineralogist.
Souther, J.G. 1977. Volcanism and Tectonic Environments in the Canadian Cordillera - A second look. The
Geological Association of Canada, Special Paper, number 16, p. 3-24.
Souther, J.G. 1986 .The western Anahim belt, root-zone of a peralkaline magma system, Canadian Journal
of Earth Sciences, v. 23, p. 895-908.
Souther, J.G. 1990. Canadian Cordillera: volcano tectonics of Canada. in Volcanoes of North America, C.
Wood and J. Kienle (ed.), Cambridge University Press, New York, p. 111-116.
Souther, J.G. 1992. The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia, Geological
Survey of Canada, Memoir 420, 320 p.
Volcanic Hazards in Canada - A Review (C.J. Hickson)
Dr. Catherine Hickson’s (Research Scientist (Volcanology) and manager GSC Vancouver Subdivision)
principal areas of expertise are in volcanology, volcanic hazards, emergency planning, and administration.
She has more than 20 years experience, much of it internationally, working in volcanic terrain. In addition
to her extensive background in fieldwork, she has considerable teaching experience. Hickson has designed
and taught several volcanological field courses and short courses both here and in South America, and led
numerous field trips. She is head of the multiagency volcanic hazards working group and the Interagency
Volcanic Event Notification Plan was formulated and implemented under her direction.
Keywords: 27 Geoscience and Society; 53 natural hazards; 86 volcanology
Invited oral presentation Thematic Session #19: Natural Hazards: Progress Towards Characterization and
Mitigation - Can earthquakes and volcanoes be predicted? J.J. Clague and S. Evans, Conveners
Contact information:
Dr. C.J. Hickson
Geological Survey of Canada
Vancouver Office
101-605 Robson Street
Vancouver, BC
V6B 5J3
(604) 666-2965 (office)
(604) 435-9644 (home)
(604) 666-7507 (fax)
[email protected]