Seguam


Facts


  • Official Name: Seguam Island
  • Seismically Monitored: No
  • Color Code: UNASSIGNED
  • Alert Level: UNASSIGNED
  • Elevation: 1054m (3458ft)
  • Latitude: 52.316
  • Longitude: -172.51
  • Smithsonian VNum: 311180
  • Pronunciation:
  • Nearby Towns:
    • Atka 72 mi (116 km) SW
    • Nikolski 159 mi (255 km) NE
    • Adak 177 mi (286 km) SW
    • Unalaska 270 mi (435 km) NE
    • Akutan 306 mi (492 km) NE
  • Subfeatures:
    • Pyre Peak
    • Wilcox
    • Moundhill

Description

From Miller and others (1998) [1] : "Seguam Island consists of the remnants of two late Quaternary calderas. Holocene volcanic cones occur in both of the calderas and a third Holocene cone lies at the east end of the island. Pyre Peak, commonly referred to as Sequam volcano, highest of the young cones, dominates the western half of the island and occupies the center of the western caldera [2] that is defined by remnants of a semi-circular ridge about 3 km in original diameter and about 700 m high. A Holocene basalt field surrounds Pyre Peak [2] extending down to shoreline. This general area has been the site of most if not all historical volcanic activity. Late Quaternary lavas and pyroclastic rocks ranging in age from 1.1 Ma to 0.03 Ma underlie the basalt. The two Holocene cones to the east are surrounded by andesite and dacite lava flows with well preserved constructional features [2] ."

Name Origin

Seguam Island was called "Ostrov Seguam" by Lieutenant Sarichev, from an Unangam Tunuu name. Lutke called it "Segouam ile" and "Gorely Ile (1836). "Goreli" is Russian for "burnt" (Orth, 1971).


References Cited

[1] Catalog of the historically active volcanoes of Alaska, 1998

Miller, T. P., McGimsey, R. G., Richter, D. H., Riehle, J. R., Nye, C. J., Yount, M. E., and Dumoulin, J. A., 1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-File Report 98-0582, 104 p.

[2] Mid-Pleistocene lavas from the Seguam volcanic center, central Aleutian arc: closed-system fractional crystallization of a basalt to rhyodacite eruptive suite, 1992

Singer, B. S., Myers, J. D., and Frost, C. D., 1992, Mid-Pleistocene lavas from the Seguam volcanic center, central Aleutian arc: closed-system fractional crystallization of a basalt to rhyodacite eruptive suite: Contributions to Mineralogy and Petrology, v. 110, p. 87-112.

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