Fourpeaked

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  • Country
  • Subregion Name
  • Primary Volcano Type
  • Last Known Eruption
  • 58.77°N
  • 153.672°W

  • 2105 m
    6904 ft

  • 312260
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

13 June-19 June 2007

AVO reported that on 6 June the Volcanic Activity Alert Level for Fourpeaked was lowered from Advisory to Normal and the Aviation Color Code was lowered from Yellow to Green based on declining rates of seismicity and gas emission.

Source: US Geological Survey Alaska Volcano Observatory (AVO)



 Available Weekly Reports


2007: June
2006: September | October


13 June-19 June 2007

AVO reported that on 6 June the Volcanic Activity Alert Level for Fourpeaked was lowered from Advisory to Normal and the Aviation Color Code was lowered from Yellow to Green based on declining rates of seismicity and gas emission.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


18 October-24 October 2006

The AVO reported that earthquake activity and gas emissions continued at Fourpeaked during 14-20 October. Steam-and-gas plumes rising from a location near the summit were visible on a recently installed web camera.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


11 October-17 October 2006

The AVO reported that earthquake activity and gas emissions continued at Fourpeaked during 7-13 October. Observations through most of the week were hindered due to cloud cover, but on 12 October AVO staff reported that two prominent vents were emitting steam and gas.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


4 October-10 October 2006

The AVO reported that volcanic unrest continued at Fourpeaked during 30 September-6 October. A seismometer that was installed on 25 September indicated ongoing low-level seismicity. Due to the limited number of seismometers, earthquake epicenters were not located. Emission rates of sulfur dioxide were high, similar to the previous week.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


27 September-3 October 2006

Volcanic unrest continued at Fourpeaked volcano during 23-29 September. Satellite observations by scientists from the University of Maryland-Baltimore County indicate that sulfur dioxide emission was continuing. Early in the week, AVO conducted several helicopter and fixed-wing missions during which observers photographed a linear series of vents running N from the summit for about 1 km. Some of the vents were vigorously emitting steam and other volcanic gases. Thermal measurements of up to 75°C were recorded at the vents, although steam was likely obscuring hotter areas. Adjacent glacial ice had been disrupted and showed signs of subsidence. Airborne gas measurements taken on 23, 24, and 30 September documented high emission rates of sulfur dioxide, hydrogren sulfide, and carbon dioxide, and a distinct sulfur smell was evident up to 50 km from the summit. An AVO status report on 3 October noted that cloudy conditions had prevented visual or satellite observations, but limited seismic data now being received did not indicate significant volcanic activity.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


20 September-26 September 2006

On the evening of 17 September the Alaska Volcano Observatory (AVO) received several reports of two discrete plumes rising from the Cape Douglas area, about 320 km SW of Anchorage. Retrospective analysis of data from the NEXRAD Doppler radar in King Salmon showed an unusual cloud starting at 1200 that day. The maximum cloud height determined by radar during the first hour of the event was 6 km (20,000 ft) a.s.l. The radar return from the cloud continued until at least 2145. A cloud of sulfur dioxide gas was observed by colleagues at the University of Maryland Baltimore County over the Cape Douglas/Fourpeaked region at 1500 using data collected by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite. On this basis all of the clouds were inferred to be volcanic in origin. Although satellite data did not detect ash during this event, AVO received reports of a trace of ashfall at Nonvianuk Lake outlet (110 km WNW) and near Homer (150 km NE).

Both fixed-wing and helicopter overflights in the Cape Douglas area 20 September confirmed the source of volcanic activity to be Fourpeaked volcano. AVO raised the Level of Concern Color Code from "Not Assigned" to YELLOW on 20 September. Fourpeaked and Douglas volcanoes are not monitored seismically. A 23 September observation flight conducted in relatively good weather permitted the first look at the summit since the event of 17 September. Observers saw a linear series of vents running N from the summit for about 1 km. Most of these vents were vigorously emitting steam and other volcanic gases. Gas measurements indicated abundant quantities of sulfur dioxide, hydrogren sulfide, and carbon dioxide.

Source: US Geological Survey Alaska Volcano Observatory (AVO)


Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2006 Sep 17 2006 Sep 17 Confirmed 2 Historical Observations Fissure trending N from summit

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Henning R A, Rosenthal C H, Olds B, Reading E (eds), 1976. Alaska's volcanoes, northern link in the ring of fire. Alaska Geog, 4: 1-88.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Motyka R J, Liss S A, Nye C J, Moorman M A, 1993. Geothermal resources of the Aleutian arc. Alaska Div Geol Geophys Surv, Prof Rpt, no 114, 17 p and 4 map sheets.

Smith R L, Shaw H R, Luedke R G, Russell S L, 1978. Comprehensive tables giving physical data and thermal energy estimates for young igneous systems of the United States. U S Geol Surv Open-File Rpt, 78-925: 1-25.

Wood C A, Kienle J (eds), 1990. Volcanoes of North America. Cambridge, England: Cambridge Univ Press, 354 p.

Poorly known Fourpeaked volcano in NE Katmai National Park consists of isolated outcrops surrounded by the Fourpeaked Glacier, which descends eastward almost to the Shelikof Strait. The orientation of andesitic lava flows and extensive hydrothermal alteration of rocks near the present 2105-m-high summit suggest that it probably marks the vent of Fourpeaked volcano. Eruptive activity during the Holocene had not been confirmed prior to the first historical eruption of Fourpeaked in September 2006. A N-trending fissure extending 1 km from the summit produced minor ashfall.