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Monte Okmok

Okmok

Volcán en escudo · United States · 1073 m

The summit of 35-km-wide Okmok has two largely overlapping 10-km-wide calderas. Both calderas formed by voluminous eruptions of tephra and pyroclastic flows during the Holocene, one about 8,250 years ago and the other about 2,400 years ago. Numerous cones and lava domes formed on the caldera floor and flanks. Historical explosive eruptions and lava flows have originated from cones within the caldera.
The summit of 35-km-wide Okmok has two largely overlapping 10-km-wide calderas. Both calderas formed by voluminous eruptions of tephra and pyroclastic flows during the Holocene, one about 8,250 years ago and the other about 2,400 years ago. Numerous cones and lava domes formed on the caldera floor and flanks. Historical explosive eruptions and lava flows have originated from cones within the caldera. · Foto: Photo by John Reeder (Alaska Division of Geological & Geophysical Surveys). · Wikimedia Commons
Tipo
Volcán en escudo
País
United States
Región
América del Norte / Aleutian Ridge Volcanic Arc
Altitud
1073 m
Coordenadas
53.430, -168.130
Última erupción
2008
Contexto tectónico
Subduction zone / Intermediate crust (15-25 km)
Forma volcánica
Shield
Roca principal
Basalt / Picro-Basalt
Resumen geológico

The basaltic Okmok shield volcano forms the NE end of Umnak Island in the Aleutian Islands. The summit of the low, 35-km-wide volcano is cut by two overlapping 10-km-wide calderas formed during eruptions about 12,000 and 2,050 years ago when dacitic pyroclastic flows reached the coast. More than 60 tephra layers from Okmok have been found overlying the 12,000-year-old caldera-forming tephra layer. Numerous cones and lava domes are present on the flanks down to the coast, including the SE-flank Mount Tulik, which is almost 200 m higher than the caldera rim. Some of the post-caldera cones show evidence of wave-cut lake terraces; more recent cones were formed after the caldera lake, once 150 m deep, disappeared. Eruptions have been reported since 1805 from cinder cones within the caldera, where there are also hot springs and fumaroles.

Resumen de Wikipedia

Resumen en inglés

Mount Okmok is a volcano on eastern Umnak Island, in the central-eastern Aleutian Islands of Alaska. Part of the Aleutian Volcanic Arc, it was formed by the subduction of the oceanic Pacific Plate under the North American Plate. Okmok is a large shield volcano capped by a 10-kilometer (6.2 mi) wide caldera. The caldera contains numerous cinder cones, their lava flows, and a few lakes. Okmok erupts mainly basaltic lava, mostly from the cones within the caldera.

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Historial de erupciones

Resumen (VEI en el tiempo)
Haga clic en una barra para ver erupciones individuales
6310 BCE~6033 BCE · 1 erupciones · VEI máx. 4210 BCE~67 · 1 erupciones · VEI máx. 61731~2008 · 17 erupciones · VEI máx. 46310 BCE4369 BCE2151 BCE210 BCE1731

Línea de tiempo detallada

  1. 2008VEI 4Observado
    2008-07-12 – 2008-08-19
    NE caldera floor
  2. 1997VEI 3Observado
    1997-02-11 – 1997-05-19
    SW part of caldera (Cone A)
  3. 1986VEI 2Observado
    1986-11-18 – 1988-02-26
    SW part of caldera (Cone A)
  4. 1983VEI 2Observado
    1983-07-08 – 1983-07-08
    SW part of caldera (Cone A)
  5. 1981VEI 3Observado
    1981-03-24 – 1981-03-24
    SW part of caldera (Cone A)
  6. 1960VEI 3Observado
    1960-10-15 – 1961-04-15
    SW part of caldera (Cone A)
  7. 1958VEI 3Observado
    1958-08-14 – 1958-08-25
    SW part of caldera (Cone A)
  8. 1945VEI 2Observado
    1945-06-04 – 1945-12-16
    SW part of caldera (Cone A)
  9. 1943VEI 1Observado
    1943-06-16 – En curso
    SW part of caldera (Cone A)
  10. 1938VEI ?Observado
    1938-07-02 – En curso
    SW part of caldera (Cone A)
  11. 1936VEI ?Estimación geológica
    1936-07-02 – En curso
    SW part of caldera (Cone A)
  12. 1931VEI 2Observado
    1931-03-21 – 1931-05-13
    Cone A?
  13. 1899VEI 3Observado
    1899-07-02 – En curso
    SW part of caldera (Cone A)
  14. 1878VEI 2Observado
    1878-07-02 – En curso
    Cone A?
  15. 1824VEI ?Observado
    1824-07-02 – 1830-07-02
    Cone B?
  16. 1817VEI 3Observado
    1817-03-01 – 1820-07-02
    Cone E? or B?
  17. 1805VEI ?Observado
    1805-07-02 – En curso
  18. 100 a. C. (±50 años)VEI 6Estimación geológica
    BCE 100 – En curso
    Okmok II caldera
  19. 6310 a. C. (±500 años)VEI 4Estimación geológica
    BCE 6310 – En curso

Enlaces externos

⚠ Solo como referencia. No apto para respuesta ante emergencias.