| Name =#redirect [[Fourpeaked Mountain ]]▼{{Current|date=April 2007}}
{{Infobox Mountain
▲| Name = Fourpeaked Mountain
| Photo =fourpeaked-fumaroles-cyrus-read1.JPG
| Caption=[[Fumaroles]] escape from Fourpeaked volcano through a fissure in [[Fourpeaked Glacier]] on [[24 September]] [[2006]]
| Elevation = 6,903 feet (2,104 metres)
| Location = [[Alaska|Alaska, USA]]
| Range = [[Aleutian Range]]
| Prominence =
| Coordinates = {{coor dm|58|46|N|153|40|W|type:mountain_region:US}}
| Topographic map = [[United States Geological Survey|USGS]] Afognak
| Type=[[Stratovolcano]]
| Age=> 10,000 years
| Last eruption= [[2006]]-[[2007]]
| First ascent =
| Easiest route =
}}
'''Fourpeaked Mountain''' also known as '''Fourpeaked volcano''' is an active [[stratovolcano]] in Alaska. The [[Alaska Volcano Observatory]] currently rates Fourpeaked as [[Volcano warning schemes|Aviation Alert Level]] Green and [[Volcano warning schemes|Volcanic-alert Level]] Normal. It is nearly completely covered by [[Fourpeaked Glacier]]. It was long a [[dormant volcano]] until it entered a new phase of activity on [[September 17]] [[2006]]. It is located in southwestern [[Alaska]], approximately 200 miles southwest of [[Anchorage, Alaska|Anchorage]], [[Alaska]] and 80 miles northwest of [[Kodiak Island]]. It lies within the [[Katmai National Park and Preserve]] on the [[Alaska Peninsula]].
[[Image:fourpeaked02.jpg|300px|thumb|left| Fourpeaked Mountain, September 17, 2006]]
[[Image:fourpeaked-map1.jpg.JPG|300px|thumb|left| AVO map shows the location of Fourpeaked volcano]]
==History==
Prior to the phase that began [[September 17]] [[2006]], Fourpeaked had been dormant for over 10,000 years, meaning its last known eruption was prior to 7994 BC.[http://www.avo.alaska.edu/activity/Fourpeaked.php]
===[[September 17]] [[2006]]===
Pilots and other civilians reported two distinct and very large steam plumes coming from Fourpeaked volcano. They were seen as far away as [[Homer, Alaska|Homer]], [[Alaska]] located northeast of Fourpeaked across [[Cook Inlet]]. Scientists on subsequent flights by USGS/AVO have discovered that volcanic gases are being vented "vigorously" near the summit. Air sampling has confirmed these findings.
===[[September 20]], [[2006]]===
The [[Alaska Volcano Observatory]] upgraded Fourpeaked from the classification "not assigned" to [[Level of Concern Color Code]] Yellow on [[September 20]] [[2006]]. This color coded system was later renamed the [[Volcano warning schemes|Aviation Alert Level]], but with the same color coding system. They also began installing seismic monitoring equipment on the mountain and using [[fixed-wing aircraft]] as well as [[helicopter]]s to monitor the volcano.
===[[September 25]] [[2006]] AVO eruption warning===
On [[September 25]] [[2006]], the AVO released the following information as part of a special information release:
"...Based on all currently available evidence, AVO believes that an eruption from
Fourpeaked in the next days to weeks is possible. Given below are some possible
future scenarios for the current unrest at Fourpeaked, listed in order, with the
most likely scenario listed first:
(1) A small to moderate eruption will occur, which may produce ash plumes
exceeding 10 km (33,000 ft) above sea level. Lava flows may also occur.
(2) No eruption occurs. Unrest gradually subsides to background levels.
(3) A large eruption will occur, which would produce ash plumes exceeding 10 km
(33,000 ft) above sea level, and possible widespread ash fall."
===[[October 3]] [[2006]]===
The Alaska Volcano Observatory completed installation of another seismometer near Fourpeaked. Almost immediately they detected an [[earthquake swarm]] of lower magnitude quakes. This behavior has continued intermittently through the present. Fourpeaked also continues to vent volcanic gasses at the same rate as revealed in earlier air sampling.
===[[February]] [[2007]]===
[[Image:fourpeaked-2-22-2007.jpg|300px|thumb| Fourpeaked Mountain with active fumaroles and sulfur deposits on February 22, 2007]]
In February, 2007 Fourpeaked began showing a relatively small but noticeable increase in activity. The Alaska Volcano Observatory reported February 8-9 that: "Three small explosive events were recorded by seismic and acoustic instruments Thursday and Friday (February 08-09) beginning at 10:36 AM AKST (1936 UTC) February 08. A possible large steam plume was observed in several partly cloudy satellite views Thursday afternoon." On February 18, the AVO reported a swarm of 13 small earthquakes under Fourpeaked,
with the largest measuring 1.8 on the [[Richter Scale]]. On February 23, the AVO conducted a gas flight and detected the continued emission of [[sulfur dioxide]] (SO2). As of February 24, the rating for the mountain remains at Yellow/Advisory.
===[[March]] [[2007]]===
The Alaska Volcano Observatory began reporting in its Daily Update on Fourpeaked volcano that "several small explosion signals" were detected overnight, apparently continuing the series of small explosions which began on February 8. These "small explosions" have continued daily through March.
=== [[June]] [[2007]] ===
Due to a significant decrease in seismic activity and reduced gas emissions following the activity of March, 2007, the Alaska Volcano Observatory downgraded the alert levels at Fourpeaked on June 5, 2007. While activity continues at the mountain, the AVO feels an eruption is now less likely. Fourpeaked will continue to be monitored by seismic instruments, by camera and through satellite imaging.
==References==
* {{VNUM | 1102-26- | Fourpeaked}}
* [http://www.avo.alaska.edu/volcanoes/volcinfo.php?volcname=Fourpeaked Alaska Volcano Observatory: Fourpeaked]
==External links==
* [http://www.usgs.gov United States Geological Survey]
* [http://www.giseis.alaska.edu UAF Geophysical Institute]
* [http://wwwdggs.dnr.state.ak.us/ Alaska Division of Geological and Geophysical Surveys]
[[Category:Current events]]
[[Category:Volcanoes of Alaska]]
[[Category:Mountains of Alaska]]
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