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Mount St Helens volcano hardly needs introduction. In its spectacular eruption in 1980, it placed itself deep into collective memory, in particular within the NW states of the USA. Prior to this eruption and its gradual reawakening, little attention had been given to the volcanic nature and the beautiful mountain was a popular landmark for excursions.
stratovolcano 2549 m / 8,363 ft
Washington, USA (mainland exept Alaska), 46.2°N / -122.18°W
Current status: dormant (1 out of 5)
Mount St. Helens volcano books
Mount St. Helens volcano eruptions:
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
Typical eruption style:Explosive
Last earthquakes nearby
Latest satellite images 
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Satellite images of Mt.St. Helens by (c) Google Earth View |
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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. ...moreThe recorded quakes have been at shallow depths between 2-7 km under the summit and ranged in magnitudes from 0 (or less) to 3 on the Richter scale, i.e. they are all tiny. Only rarely, they exceeded magnitude 2 and only a very few might have been felt by persons being very close. USGS volcanologists and seismologists interpret the vertical area where these quakes occurred as the area where a small amount of fresh magma has been rising into the volcano's plumbing system (a magma chamber). Magma rises, pressurizes surrounding rock to make space and causes fracturing = tiny quakes. [ less] [ read all]
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. ...moreSeismicity persisted at low levels. [ less] 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. ...more
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. ...more
Show more news
Wed, 17 Jan 2007, 23:13
The lava dome at Mount St. Helens continues to grow slowly, accompanied by low-level seismicity. ...more
Thu, 23 Nov 2006, 00:12
The lava dome at Mount St. Helens continues to grow, and producing a prominent spine that rises by about 2-3 meters per day. Small tremors are frequently registered at the volcano, believed to be caused by the movements of the spine being pushed up by pressurized magma in the conduit. ...more
Tue, 30 May 2006, 17:13
On 29 May at 09h08 local time, an ash and gas plume rose to 5-6 km altitude above the new lava dome of Mt. St. Helens. As CVO reports, the event was not caused by explosive activity, but rather intense degassing and a partial collapse of the new lava dome, accompanied by a quake of magnitude 3.1.
Tue, 9 May 2006, 07:41
The 300 ft spine of Mt. St. Helens as on 6 May, 2006 (USGS photo). The lava dome inside Mt. St. Helens' crater continues to grow. It has been forming a giant, spectacular spine, about 300 ft high and growing at about 4-5 in (ca. 12-15cm) per day.
The park has reopened the Johnston Ridge Observatory viewing point.
Thu, 13 Apr 2006, 08:45
Growth of the new lava dome inside the crater of Mount St. Helens continued during 5-10 April, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. ...more
Sat, 18 Feb 2006, 15:13
No big changes: the growth of the new lava dome inside the crater of Mt. St. Helens continues, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash.
Thu, 9 Feb 2006, 10:01
The lava dome of Mt. St. Helens continues slowly, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash.
Thu, 9 Jun 2005, 00:07
Over the past week, the new lava dome with a prominant spine continued to grow, at rates of up to several cm per day in some locations. Seismicity remains at low levels and only minor emissions of ash occrred.
Wed, 1 Jun 2005, 22:18
During 25-31 May, growth of the new lava dome inside the crater of Mount St. Helens continued, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. Lava extrusion continued at the N end of the new lava dome, while the high spines continued to crumble. Other parts of the lava dome moved at the relatively low velocity of about 0.3 m per day or remained stagnant. St Helens remained at Volcano Advisory (Alert Level 2); aviation color code Orange. ...more---
(Source: GVP/USGS Weekly Volcanic Activity Report, 25-31 May 2005) [ less]
Mon, 4 Apr 2005, 10:29
CVO (the Cascades Volcano Ovservatory, USGS) reports that the lava dome inside Mt. St. Helens' crater continues slowly to grow. Seismicity is low, and other eruptive activiy is limited to small emissions of steam and volcanic gases, and minor production of ash.
CVO warms of the danger of small lahars and the possibility that the eruption might intensify with little or no warning at any time. ...more [ read all]
Tue, 22 Mar 2005, 10:50
As press reports on March 22, some areas around Mt. St. Helens volcano, that had been closed for visitors after the reawakening of Mt. St. Helens in Oct. 2004 are being reopened, since activity has been drastically decreasing. This includes the Johnston Ridge Observatory, was evacuated on October 2 as volcanic activity increased and now scheduled for reopening on 6th of May...
At the moment, the mountain will remain closed above the Loowit Trail, roughly the tree line, keeping the popular south-side climbing route off limits. Ridge-top trails north of the volcano and the Mount Margaret backcountry, a permit-only area, will reopen as conditions permit. Parts of the Loowit and Truman trails on the north side will stay closed because of possible mud flows.
BackgroundPrior 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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