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Gunung St. Helens

St. Helens

Stratovolkan · United States · 2549 m

The 1980 eruption of Mount St. Helens dramatically altered the conical profile of the volcano. The eruption left a 2 x 3.5 km wide horseshoe-shaped crater, seen here from the NNE beyond Spirit Lake (center). The landslide of 18 May lowered the summit by 400 m and produced a highly mobile debris avalanche that swept into Spirit Lake and traveled down the North Fork Toutle River. The associated northward-directed lateral blast devastated about 600 km2.
The 1980 eruption of Mount St. Helens dramatically altered the conical profile of the volcano. The eruption left a 2 x 3.5 km wide horseshoe-shaped crater, seen here from the NNE beyond Spirit Lake (center). The landslide of 18 May lowered the summit by 400 m and produced a highly mobile debris avalanche that swept into Spirit Lake and traveled down the North Fork Toutle River. The associated northward-directed lateral blast devastated about 600 km2. · Foto: Photo by Lyn Topinka, 1981 (Cascades Volcano Observatory, U.S. Geological Survey). · Wikimedia Commons
Tipe
Stratovolkan
Negara
United States
Wilayah
North America Volcanic Regions / High Cascades Volcanic Arc
Ketinggian
2549 m
Koordinat
46.200, -122.180
Letusan terakhir
2008
Kondisi tektonik
Subduction zone / Continental crust (> 25 km)
Bentuk lahan
Composite
Batuan utama
Dacite
Ringkasan geologi

Prior to 1980, Mount St. Helens was a conical volcano sometimes known as the Fujisan of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km breached crater now partially filled by a lava dome. There have been nine major eruptive periods beginning about 40-50,000 years ago, and it has been the most active volcano in the Cascade Range during the Holocene. Prior to 2,200 years ago, tephra, lava domes, and pyroclastic flows were erupted, forming the older edifice, but few lava flows extended beyond the base of the volcano. The modern edifice consists of basaltic as well as andesitic and dacitic products from summit and flank vents. Eruptions in the 19th century originated from the Goat Rocks area on the N flank, and were witnessed by early settlers.

Ringkasan Wikipedia

Gunung St. Helens adalah sebuah gunung berapi aktif yang terletak di Skamania County, Washington, Amerika Serikat. Gunung ini adalah bagian dari Barisan Pegunungan Cascade dan dahulu pernah dikenal dengan nama Louwala-Clough. Gunung ini paling terkenal akan letusannya yang terjadi pada 18 Mei 1980. Letusan tersebut merupakan letusan gunung berapi terparah baik dari segi kekuatan letusan maupun kerugian ekonomi sepanjang sejarah Amerika Serikat. 57 orang tewas, dan puncak gunung berkurang dari 2.950 meter menjadi 2.550 m. Lokasi letusan kini menjadi kawasan Monumen Nasional Gunung Berapi Gunung St. Helens.

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Riwayat letusan

Ringkasan (VEI dari waktu ke waktu)
Klik pada bar untuk melihat letusan individu
2340 BCE~2143 BCE · 1 letusan · VEI maks. 52143 BCE~1945 BCE · 1 letusan · VEI maks. ?1945 BCE~1748 BCE · 2 letusan · VEI maks. 61748 BCE~1550 BCE · 2 letusan · VEI maks. ?1353 BCE~1155 BCE · 1 letusan · VEI maks. ?1155 BCE~958 BCE · 2 letusan · VEI maks. ?958 BCE~760 BCE · 2 letusan · VEI maks. ?563 BCE~365 BCE · 1 letusan · VEI maks. 5365 BCE~168 BCE · 3 letusan · VEI maks. ?168 BCE~29 · 1 letusan · VEI maks. ?29~227 · 2 letusan · VEI maks. 0227~424 · 3 letusan · VEI maks. 0622~819 · 1 letusan · VEI maks. ?1412~1609 · 3 letusan · VEI maks. 51609~1807 · 2 letusan · VEI maks. 51807~2004 · 17 letusan · VEI maks. 52340 BCE1353 BCE168 BCE8191807

Garis waktu rinci

  1. 2004VEI 2Teramati
    2004-10-01 – 2008-01-27
    South of 1980-1986 lava dome
  2. 1990VEI 3Teramati
    1990-11-05 – 1991-02-14
    North side of lava dome
  3. 1989VEI 2Teramati
    1989-12-07 – 1990-01-06
    North side of lava dome
  4. 1980VEI 5Teramati
    1980-03-27 – 1986-10-28
    Summit and north flank
  5. 1921VEI ?Perkiraan geologi
    1921-03-18 – Berlangsung
  6. 1903VEI ?Perkiraan geologi
    1903-09-15 – Berlangsung
  7. 1898VEI ?Perkiraan geologi
    1898-04-05 – Berlangsung
  8. 1857VEI 2Teramati
    1857-04 – Berlangsung
  9. 1854VEI 2Teramati
    1854-02 – 1854-04
    North flank
  10. 1853VEI 2Teramati
    1853-03-15 – 1853-08
    North flank
  11. 1850VEI 2Teramati
    1850-03 – 1850-05
    North flank
  12. 1849VEI 2Perkiraan geologi
    1849 – Berlangsung
    North flank
  13. 1848VEI 2Teramati
    1848-04-01 – Berlangsung
  14. 1847VEI 2Teramati
    1847-03-26 – 1847-03-30
    North flank (Goat Rocks)
  15. 1842VEI 3Teramati
    1842-11-22 – 1845-09-18
    North flank (Goat Rocks)
  16. 1835VEI 2Teramati
    1835-03 – Berlangsung
    North flank (Goat Rocks area)
  17. 1831VEI 3Teramati
    1831-08 – Berlangsung
    North Flank (Goat Rocks area)
  18. 1800VEI 5Perkiraan geologi
    1800-01-15 – Berlangsung
    N flank--Goat Rocks area
  19. 1610 (±40 tahun)VEI ?Perkiraan geologi
    1610 – Berlangsung
    Pre-1980 summit dome
  20. 1525 (±25 tahun)VEI ?Perkiraan geologi
    1525 – Berlangsung
  21. 1482VEI 5Perkiraan geologi
    1482-01-15 – Berlangsung
  22. 1480VEI 5Perkiraan geologi
    1480-01-15 – Berlangsung
  23. 780 (±300 tahun)VEI ?Perkiraan geologi
    780 – Berlangsung
    NE flank (Sugar Bowl)
  24. 420VEI ?Perkiraan geologi
    420 – Berlangsung
  25. 270VEI ?Perkiraan geologi
    270 – Berlangsung
  26. 230VEI 0Perkiraan geologi
    230 – Berlangsung
  27. 190VEI ?Perkiraan geologi
    190 – Berlangsung
    Lower E flank (East Dome)
  28. 100VEI 0Perkiraan geologi
    100 – Berlangsung
    SW flank (Cave basalts)
  29. 100 SMVEI ?Perkiraan geologi
    BCE 100 – Berlangsung
  30. 220 SMVEI ?Perkiraan geologi
    BCE 220 – Berlangsung
    NNE flank (Dogs Head)
  31. 250 SMVEI ?Perkiraan geologi
    BCE 250 – Berlangsung
  32. 280 SMVEI ?Perkiraan geologi
    BCE 280 – Berlangsung
  33. 530 SMVEI 5Perkiraan geologi
    BCE 530 – Berlangsung
  34. 800 SMVEI ?Perkiraan geologi
    BCE 800 – Berlangsung
  35. 830 SM (±75 tahun)VEI ?Perkiraan geologi
    BCE 830 – Berlangsung
  36. 1010 SMVEI ?Perkiraan geologi
    BCE 1010 – Berlangsung
  37. 1100 SMVEI ?Perkiraan geologi
    BCE 1100 – Berlangsung
  38. 1180 SMVEI ?Perkiraan geologi
    BCE 1180 – Berlangsung
  39. 1610 SMVEI ?Perkiraan geologi
    BCE 1610 – Berlangsung
  40. 1680 SMVEI ?Perkiraan geologi
    BCE 1680 – Berlangsung
  41. 1770 SM (±100 tahun)VEI 5Perkiraan geologi
    BCE 1770 – Berlangsung
  42. 1860 SMVEI 6Perkiraan geologi
    BCE 1860 – Berlangsung
  43. 2100 SM (±300 tahun)VEI ?Perkiraan geologi
    BCE 2100 – Berlangsung
  44. 2340 SMVEI 5Perkiraan geologi
    BCE 2340 – Berlangsung

Tautan eksternal

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