Mount St. Helens s

Ten Year Anniversay of Mount St. Helens Reawakening

Longview, Washington – Baby boomers and Gen Xers all recall the news coverage that Mount St. Helens captured when the volcano exploded on May 18, 1980. The volcanic activity from the mountain continued for another six years before abruptly going dormant. Then to everyone’s surprise, the volcano began reawakening as a second lava dome began to arise ten years ago today. A lava dome is a roughly circular shaped mount of viscous (very thick) lava formed by the slow expulsion of lava from a volcano. By the time the second lava dome had formed, it was now 2007 and its height was 328m (1,076 ft) above the crater floor. The massive 1980 explosion marked the creation of the first lava dome which concluded in 1986.

These days, the volcano does not capture the public’s attention nearly as much as it did back in 2004. However, scientists with the United States Geological Survey (USGS) are using the 10-year anniversary of the volcano’s awakening to bring attention to newly installed eruption warning technology. The USGS reminds the public that the volcano is still active, and it is still in the process of rebuilding. Admittedly, no new lava has been expulsed since 2008, but a number of factors contribute to the shape of the lava dome changing.

Part of the changes are due to the cooling of the dome, and its subsequent fracturing. Lava domes are largely composed of basaltic and andesitic rock which come apart with relative ease compared to other types of rock. The USGS is also aware of the fact that deep within the volcano at a depth of 5 miles below the earth’s surface, magma is pressurizing. Careful measurements are regularly taken to gauge the rate at which the magma is charging which may indicate when a third lava dome will be created. By all comparisons, the instrumentation being used today is more accurate and reliable than what was used ten years ago.

Rocky Kolberg - Rocky Kolberg The May 18 eruption. Composite photograph from 35 miles (60 km) west in Toledo, Washington. The ash-cloud stem is 10 miles (16 km) wide, and the mushroom top is 40 miles (64 km) wide and 15 miles (24 km) high. The footprint of the cloud stem is roughly the same as the devastated area north of the mountain where the forest was knocked down and which three decades later is still relatively barren.  Mt. St. Helens mushroom cloud, 40 miles wide and 15 miles high. Camera location: Toledo, Washington, 35 miles west-northwest of the mountain. The picture is a composite of about 20 separate images.

Rocky Kolberg – Rocky Kolberg
The May 18 eruption. Composite photograph from 35 miles (60 km) west in Toledo, Washington. The ash-cloud stem is 10 miles (16 km) wide, and the mushroom top is 40 miles (64 km) wide and 15 miles (24 km) high. The footprint of the cloud stem is roughly the same as the devastated area north of the mountain where the forest was knocked down and which three decades later is still relatively barren.
Mt. St. Helens mushroom cloud, 40 miles wide and 15 miles high. Camera location: Toledo, Washington, 35 miles west-northwest of the mountain. The picture is a composite of about 20 separate images.

News source(s):
http://www.kgw.com/story/news/local/mt-st-helens/2014/09/26/mount-st-helens-shows-signs-of-reawakening/16288495/