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Amerika Serikat · Gunung api perisai

Mount Okmok

Okmok

Tipe
Gunung api perisai
Ketinggian
1073 m
Letusan terakhir
2008
Mount Okmok
Foto: J. Reeder. Alaska Division of Geological and Geophysical Surveys · Public domain · Wikimedia Commons
Tipe
Gunung api perisai
Negara
Amerika Serikat
Wilayah
Amerika Utara / Aleutian Ridge Volcanic Arc
Ketinggian
1073 m
Koordinat
53.430, -168.130
Letusan terakhir
2008
Kondisi tektonik
Zona subduksi / Kerak menengah (15-25 km)
Bentuk lahan
Perisai
Batuan utama
Basal / Pikrobasal
Ringkasan geologi

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.

Ringkasan Wikipedia

Ringkasan Inggris

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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Riwayat letusan

19 tercatatGlosarium
Ringkasan (VEI dari waktu ke waktu)
Klik pada bar untuk melihat letusan individu · Gunakan tombol panah untuk berpindah batang, Enter untuk membuka
6310 SM~6033 SM · 1 letusan · VEI maks. 4210 SM~67 · 1 letusan · VEI maks. 61731~2008 · 17 letusan · VEI maks. 46310 SM4369 SM2151 SM210 SM1731

Garis waktu rinci

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

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