Mount Wrangell
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| Mount Wrangell | |
|---|---|
 Mount Wrangell, 1987 |
|
| Elevation | 14,163 ft (4,317 m) |
| Location | Alaska, USA |
| Range | Wrangell Mountains |
| Prominence | 5,563 ft (1,696 m) |
| Coordinates | |
| Topo map | USGS Gulkana A-1 |
| Type | Shield volcano |
| Volcanic arc/belt | Wrangell Volcanic Field |
| Last eruption | 1999 |
Mount Wrangell is a massive shield volcano located in Wrangell-St. Elias National Park and Preserve in southeastern Alaska, United States. The shield rises over 12,000 ft (3700 m) above the Copper River to its southwest. Its volume is over 220 mi³ (900 km³), making it more than twice as massive as Mount Shasta in California, the largest stratovolcano by volume in the Cascades.
An ice-filled caldera 4 by 6 km in diameter lies at the top of Wrangell's broad shield. The caldera was apparently formed by subsidence rather than large explosive eruptions. The caldera is in turn rimmed by three small craters, which often display fumarolic activity with steam plumes that can sometimes be seen from a distance. The main summit is on the north side of the caldera, while the west summit rises to 14,013 feet (4,271 m). The summit region above 13,000 ft (4000 m) in elevation is over 2 x 5 miles (3 x 8 km) in size. A very large cinder cone, 13,009 ft (3,965 m) Mount Zanetti, rises nearly 1000 ft (300 m) above the northwest flank of Wrangell and is the source of some lava flows.
Wrangell is unusual in that despite being a shield volcano, it is made mainly of andesite rather than basalt, which forms most shield volcanoes in other parts of the world. A few other volcanoes in the Wrangell Volcanic Field also share this feature. Andesite is a volcanic rock found mainly in stratovolcanoes and tends to form short, stubby flows. How Wrangell grew into a shield volcano is poorly understood, but its lava flows appear to have been voluminous and were also probably generated by high eruption rates.
Wrangell is the only volcano in the Wrangell Volcanic Field to have had historically recorded eruptions, generally in the form of small steam and ash explosions. The amount of geothermal heat being emitted by Wrangell has been increasing since the 1950s, raising the possibility of a future eruption. Also, the heat flux has been high enough to melt ice around the craters and create ice caves.
[edit] See also
[edit] References
- Richter, Donald H.; Danny S. Rosenkrans and Margaret J. Steigerwald (1995). Guide to the Volcanoes of the Western Wrangell Mountains, Alaska. USGS Bulletin 2072.
- Winkler, Gary R. (2000). A Geologic Guide to Wrangell—Saint Elias National Park and Preserve, Alaska: A Tectonic Collage of Northbound Terranes. USGS Professional Paper 1616. ISBN 0-607-92676-7.
- Richter, Donald H.; Cindi C. Preller, Keith A. Labay, and Nora B. Shew (2006). Geologic Map of the Wrangell-Saint Elias National Park and Preserve, Alaska. USGS Scientific Investigations Map 2877.
- Wood, Charles A.; Jürgen Kienle, eds. (1990). Volcanoes of North America. Cambridge University Press. ISBN 0-521-43811-X.
- Alaska Volcano Observatory: Mount Wrangell
- Smithsonian Institution Global Volcanism Program: Mount Wrangell
[edit] External links
- Mount Wrangell is at coordinates Coordinates:
