Seguam

Photo of this volcano
  • United States
  • Alaska
  • Stratovolcano(es)
  • 1993 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 52.315°N
  • 172.51°W

  • 1054 m
    3457 ft

  • 311180
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: August 1993 (BGVN 18:08) Citation IconCite this Report


Ash eruption to 2,500 m altitude

On 19 August, U.S. Coast Guard observers reported that Pyre Peak . . . was continuing to erupt from a vent ~180 m below the summit. A dark ash plume over the volcano that day reached an altitude of 2,500 m and drifted ESE. No reports of ashfall in the sparsely populated region were received. U.S. Coast Guard observers reported that Pyre Peak was continuing to erupt in late August, but poor weather conditions prevented observers from confirming continued activity through 3 September. Frequent poor weather and limited air traffic combine to make tracking of activity at this remote island volcano difficult.

Information Contacts: AVO.

The Global Volcanism Program has no Weekly Reports available for Seguam.

Bulletin Reports - Index


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

03/1977 (NSEB 02:03) Lava fountaining from a 1-km-long rift seen on 6 March

12/1992 (BGVN 17:12) Small ash eruptions

05/1993 (BGVN 18:05) Ash eruptions reported

07/1993 (BGVN 18:07) Ash eruptions to 2,400 m height; lava flow

08/1993 (BGVN 18:08) Ash eruption to 2,500 m altitude




Information is preliminary and subject to change. All times are local (unless otherwise noted)


March 1977 (NSEB 02:03) Citation IconCite this Report


Lava fountaining from a 1-km-long rift seen on 6 March

Jürgen Kienle reported that on 6 March at about 0400, the crew of the USCG Cutter Mellon observed and photographed eruptive activity at the 750-m level of Pyre Peak, Seguam Island. Eight lava fountains rising to an estimated 90 m were observed along a l-km radial rift 2.5 km SW of Pyre Peak summit. Activity appeared to be progressing NE (towards the summit).

A lava flow formed and divided into two tongues. The larger was approximately 2.5 km long and l km wide. The smaller moved toward the S, and was approximately l km long and 0.5 km wide. Three dense black clouds were erupted from the vent during 2 hours of observation, after which the Mellon departed.

The nearest short-period seismometers, 225 km to the E (Nikolski), and 300 km to the W (Adak), were too far away to register any unusual earthquake activity.

Thomas Miller reported that on 8 March, a Reeve Aleutian Airlines flight passed over Seguam at low altitude. The pilot reported that lava effusion and fountaining had ended, but that a considerable amount of steam, possibly containing some ash, was being emitted from the fissure. Lava flows had not reached the sea. Poor weather during much of the year hampers aerial observation.

Several other ship reports of eruptions in the area have been received in the past several years. Seguam is uninhabited.

Information Contacts: J. Kienle, Univ. of Alaska; T. Miller, USGS, Anchorage.


December 1992 (BGVN 17:12) Citation IconCite this Report


Small ash eruptions

Small ash eruptions from a satellite cone 1.5 km S of the W caldera's central cone (Pyre Peak) (figure 1) were observed on 27 and 30 December 1992 by the U.S. Coast Guard . . . . Activity on the 27th consisted of an ash plume that extended 24 km N from the island at 1,200 m altitude. On 30 December, discrete explosions ejected ash to several hundred meters height. Ash fell S of the vent, which appears to be located near the N end of a line of lava fountains observed during the 1977 eruption. The vent site consists of a cluster of cinder cones and craters, which was probably the source of a prehistoric basaltic lava field covering ~21 km2.

Figure (see Caption) Figure 1. Topographic map of Seguam Island showing the area of December 1992 activity (dot S of Pyre Peak). The line SE from the vent site represents the 1977 lava fountains, and the outline shows the 1977 lava flows. Courtesy of AVO.

Information Contacts: Michael Doukas, USGS Anchorage.


May 1993 (BGVN 18:05) Citation IconCite this Report


Ash eruptions reported

A small ash burst, rising through clouds near Pyre Peak, was reported by the U.S. Coast Guard on 28 May. A plume to 3 km altitude was reported on 2 June by the NWS, but it is not known if the plume contained ash.

Information Contacts: AVO.


July 1993 (BGVN 18:07) Citation IconCite this Report


Ash eruptions to 2,400 m height; lava flow

Heavy ash eruptions rising 900-1,200 m were reported the morning of 31 July by the U.S. Coast Guard. A lava flow was also noted. According to these observers, the volcano was still erupting sporadically on 10 August, with light- to dark-gray ash plumes rising 2,400 m above the summit. Reports from Atka Island (~110 km W) indicate that weather conditions have frequently prevented observations.

Information Contacts: AVO.


August 1993 (BGVN 18:08) Citation IconCite this Report


Ash eruption to 2,500 m altitude

On 19 August, U.S. Coast Guard observers reported that Pyre Peak . . . was continuing to erupt from a vent ~180 m below the summit. A dark ash plume over the volcano that day reached an altitude of 2,500 m and drifted ESE. No reports of ashfall in the sparsely populated region were received. U.S. Coast Guard observers reported that Pyre Peak was continuing to erupt in late August, but poor weather conditions prevented observers from confirming continued activity through 3 September. Frequent poor weather and limited air traffic combine to make tracking of activity at this remote island volcano difficult.

Information Contacts: AVO.

Eruptive History


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


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1993 May 28 1993 Aug 31 (in or after) Confirmed 2 Historical Observations Near Pyre Peak
1992 Dec 27 1992 Dec 30 Confirmed 2 Historical Observations Pyre Peak (1.5 km south of summit)
1977 Mar 6 1977 Mar 8 (?) Confirmed 1 Historical Observations Pyre Peak (2.5 km SE of summit)
[ 1927 ] [ Unknown ] Uncertain    
1902 Unknown Confirmed 3 Historical Observations
1892 Apr 15 ± 45 days Unknown Confirmed 3 Historical Observations
1891 Dec Unknown Confirmed 2 Historical Observations
[ 1827 ] [ Unknown ] Uncertain    
1786 1790 Confirmed   Historical Observations
0250 ± 500 years Unknown Confirmed   Uranium-series West of Wilcox volcano
4050 BCE ± 4000 years Unknown Confirmed 0 Uranium-series W flank of cone in eastern caldera
5100 BCE ± 2000 years Unknown Confirmed 0 Uranium-series W flank of cone in eastern caldera
7300 BCE ± 2250 years Unknown Confirmed 5 Ar/Ar Wilcox volcano

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Photo Gallery


Lava fountains rise above a fissure on Seguam volcano on March 8, 1977. This view from the south shows part of the 1.5-km-long eruptive fissure SE of Pyre Peak, the volcano's summit. Black lava flows move across the snow from the fissure and diverge around an older, snow-covered cone at the lower right. Two large late-Quaternary calderas occur on Seguam Island, both of which contain Holocene cones. Pyre Peak, in the western caldera, is surrounded by fresh lava fields and dominates the western half of the island.

Photo by U.S. Coast Guard, 1977 (courtesy of Alaska Volcano Observatory).
See title for photo information.
The snow-dappled slopes of Pyre Peak are seen from near the western tip of Seguam Island. The elliptical, 11.5 x 24 km island contains two calderas, each with a Holocene central volcano. A third Holocene cone lies at the eastern end of the island. Pyre Peak was constructed within the 3-km-wide westernmost caldera. The 1054-m-high cone rises 1 km above the caldera floor and has been the source of most of the historical eruptions of Seguam volcano.

Photo by Steve Ebbert, 1996 (U.S. Fish and Wildlife Service).
See title for photo information.

Smithsonian Sample Collections Database


There are no samples for Seguam in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

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