Page 144 - Volcano and Geothermal Tourism

Alaska’s Volcanoes 121

Geophysical aspects and jetliners, and caused several days worth of airport
history of activity closures and airline cancellations in Anchorage
and on the Kenai peninsula (Casadevall, 1994).
Alaska’s volcanoes and volcanic fields with an active Drifting ash clouds disrupted air traffic as far
past are mostly found in the Aleutian Arc extending away as Texas. Mt Redoubt is within Lake Clark
over 2500km out into the north Pacific Ocean National Park and Preserve and is accessible by
towards Kamchatka and enclosing the Bering Sea, small aircraft to the glaciers and the Drift River
or on the mainland. Aleutian Arc volcanism is the gravel banks.
result of active subduction of the Pacific Plate The three eruptions of Mt Spurr’s crater peak
beneath the North American Plate, and since 1741 (125km west of Anchorage and only accessible by
≅ 44 Alaskan volcanoes have had more than 230 small charter aircraft) in 1992 deposited ash on
confirmed eruptions. For the past 40 years – a Anchorage and surrounding communities, closed
period in which there are fairly good records – airports, made ground transportation difficult and
Alaska has averaged more than two eruptions per disrupted air traffic as far east as Cleveland, Ohio.
year. However, while the frequency of reports of Mt Augustine is a stratovolcano on Augustine
eruptions is higher now than in the past, and was Island in south-western Cook Inlet 80km south-
increasing during the 20th century, the increases west of Anchorage. This volcano last erupted in
from 1880 to the present day are probably the result 2006 and is especially dangerous for its debris
of increased population, communications and travel, avalanche activity, which can cause tsunamis in
rather than an actual increase in the frequency of Cook Inlet.
eruptions (Rosi et al, 2003). Mt Iliamna is a glacier-carved stratovolcano
This case study looks at the most important of located approximately 215km south-west of
the major volcanoes of Alaska in order to illustrate Anchorage on the west side of the lower Cook
their impact on tourism and on surrounding Inlet. Holocene eruptive activity from Iliamna is
communities. The first of these, Novarupta (Alaska indicated, all before the European settlement of
peninsula) is the least topographically prominent Alaska. However, fumaroles located at about
volcano in the Katmai area and was formed 2740m elevation on the eastern flank produce
during a major eruption in 1912. This eruption nearly constant plumes of condensate and minor
was the world’s largest during the 20th century amounts of sulphurous gases. These plumes are
and produced a large amount of tephra and the quite vigorous and have resulted in numerous
renowned Valley of Ten Thousand Smokes (VTTS) pilot reports and early historical accounts of
ash flow (Rosi et al, 2003, pp218–219). Ash from ‘eruptions’ at Iliamna volcano, which last erupted
Novarupta spread worldwide and locally roofs in during 1876 (Schafer and Nye, 2008).
Kodiak City collapsed due to the weight of the
ash; six villages close to Katmai and Novarupta Risk factors
were permanently abandoned. Novarupta is The Global Volcanism Program database for the
accessible on foot and is uninhabited wilderness. volcanoes of Alaska currently contains 92 Holocene
The 1989–1990 eruptions from Mt Redoubt volcanoes and one Pleistocene volcano with
on the other hand, were the second most costly in thermal activity, and most of these are located
the history of the United States, and had significant along the 2500km long Aleutian Arc, which
impact on the aviation and oil industries as well extends westward to Kamchatka and forms the
as the people of the Kenai peninsula where, northern portion of the Pacific ‘ring of fire’.
during periods of continuous ash fallout, schools Other volcanoes that have been active in the last
were closed and some individuals experienced few thousand years exist in south-eastern Alaska
respiratory problems. At the Drift River oil (such as Mt Edgecumbe) and in the Wrangell
terminal, lahars and lahar run-out flows threatened Mountains. Smaller volcanoes, some active within
the facility and partially inundated the terminal on the last 10,000 years, are found in interior Alaska
2 January 1990 (Dorava and Meyer, 1994). The and in western Alaska as far north as the Seward
Redoubt eruption also damaged five commercial peninsula.

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