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Diaporama
Mount St. Helens volcan
stratovolcan 2549 m / 8,363 ft
Washington, USA (mainland exept Alaska), 46.2°N / -122.18°W
Condition actuelle: normal / en sommeil (1 sur 5)
Mount St. Helens webcams / données en temps réel | Reports
Mount St. Helens livres
Eruptions du volcan Mount St. Helens:
2004-08, 1990-91, 1989-90, 1980-86 (18 May 1980: Plinian eruption), 1921(?), 1903(?), 1898?, 1857, 1854, 1853, 1850, 1849(?), 1848, 1847, 1842-45, 1835, 1831
Style éruptif tipique:
Explosive
Derniers séismes proches
Derniers images satellite
Satellite images of Mt.St. Helens by (c) Google Earth View
Satellite images of Mt.St. Helens by (c) Google Earth View
Mt. St. Helens in Sept. 2005, seen from the N with its grand amphitheatre left by the collapse during the 18 May, 1980 eruption (photo courtesy: W Heise).
Mt. St. Helens in Sept. 2005, seen from the N with its grand amphitheatre left by the collapse during the 18 May, 1980 eruption (photo courtesy: W Heise).
 

Mt. St. Helens volcano updates:

Tue, 10 May 2016, 11:03
Earthquakes under Mount St. Helens volcano during 1988-2016; magmatic recharge swarms are marked, along with the most recent earthquake swarm. (image: USGS / Cascade Volcano Observatory via Eruptions Blog)
Since the beginning of 2016, a swarm of small earthquakes has been occurring at under the volcano, suggesting that another phase of magma recharge is currently taking place. ...plus [lire toutes]
Sat, 20 Apr 2013, 08:25
(Very) tiny earthquakes occur regularly at the volcano, but nothing suggests anything unusual going on at the volcano for the moment.
Thu, 21 Feb 2008, 14:55
During 13-19 February lava-dome growth at Mount St. Helens continued. ...plus
Wed, 6 Feb 2008, 21:36
At 23-29 January lava-dome growth at Mount St. Helens continued. A steam plume that rose from the dome and slightly above the crater rim was visible on 25 January.
Sat, 3 Nov 2007, 18:08
Deformation-monitoring instruments indicated that during
24-30 October lava-dome growth at Mount St. Helens continued.
Thu, 27 Sep 2007, 19:48
From 19-25 September lava-dome growth at Mount St. Helens continued.
Fri, 14 Sep 2007, 08:50
No significant changes have been registered at Mt. St. Helens. CVO's instruments monitoring the volcano indicate that the lava dome continues be active and grow slowly.
Thu, 30 Aug 2007, 23:47
Data from deformation-monitoring instruments indicated that during 22-28 August lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. Clouds occasionally inhibited visual observations.
Thu, 5 Apr 2007, 22:08

Data from deformation-monitoring instruments and observations from a remote camera showed that during 28 March-3 April, lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5 and occasionally larger earthquakes. On 3 April, a GPS unit on an active spine showed W-ward movement at a rate of about 30 cm/day.

...plus
Thu, 22 Mar 2007, 19:44

Over the past weeks and months, the lava dome and spine inside Mount St. Helens' crater continued to grow, accompanied by generally low levels of seismicity.

...plus

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Background

Prior to the 1980 eruption, Mount St. Helens formed a conical, youthful volcano sometimes called the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by collapse of the slope, that left a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens is a very young volcano and only about 40-50,000 years old.
It has been the most active volcano in the Cascade Range during the past 10,000 years, and the modern edifice was constructed during the last 2,200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century were witnessed by early settlers.


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Sources:

USGS Cascades Volcano Observatory
St. Helens Information from the Global Volcanism Program


 

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