Daffodil Lane

When Mt. Saint Helens violently erupted on May 18, 1980 it set off a series of events that ultimately affected overall global air quality. The side effects of this particular eruption were far reaching. In order to understand what ultimately transpired in terms of air pollution we must first take a brief look at the eruption itself. The way the eruption occurred gives a larger picture of the actual global implications of the volcano erupting.

Mt. Saint Helens is one of fifty active volcanoes located in the United States and is known as a subduction volcano. On May 18, 1980 Mt. Saint Helens erupted in a violent explosion that destroyed a land area the size of Austin, Texas. The explosion was 700 times more powerful than the atomic bomb that destroyed Hiroshima during World War II. The explosion was so powerful that the top 1,300 feet of the mountain disappeared in the initial explosion due to sheer force. This amounts to the mountain losing roughly one-seventh of its original height, tumbling from 9,700 feet to a mere 8,400 feet. (The National Oceanic and Atmospheric Administration [NOAA], ND) To put that in perspective the gaping hole that was left is roughly 625 meters deep, 2 kilometers wide and 2.7 kilometers long. (Boer & Sanders, 2002)

The primary blast wave from the explosion moved at speeds of around 600 miles per hour snapping trees and destroying everything in its path, including animals, homes and even human beings. A total of 57 people were confirmed dead. The mushroom cloud created by the violent explosion took mere minutes to travel high into the atmosphere. It rose at a mile a minute or roughly translated 15 miles into the atmosphere in a matter of approximately 15 minutes.

The eruption cloud eclipsed the sun in Yakima which is roughly 150 miles away from the mountain itself, and the ash choked cities thousands of miles away as the volcanic plume traveled all the way around the globe, taking the pollution it carried with it. The eruption also created a lehar (a volcanic mudslide consisting of mud, rock and water that is much like wet concrete) that traveled 100 miles from the blast zone and also destroyed most everything in its path. Some even argue that lehars are the most lethal part of a volcanic eruption, although others argue that it is actually the pyroplastic flow. (The Discovery Channel [TDC], 2005) The above description of what occurred at Mt. Saint Helens on May 18, 1980 leaves little room to imagine that a volcanic eruption is anything but violent.

Although the amount of ash that was produced by the 1980 eruption was small compared to other historic eruptions, it still caused many problems. In Washington and Idaho 8 inches of ash fell. The ash caused short circuits in electrical transformers onboard aircraft that flew through the ash cloud, it caused air filters in vehicles to clog thus rendering police and ambulance services inoperable, it brought ground traffic in the area to a standstill, closed highways, turned day into night and affected the ability to breath causing those in the area to have to wear masks in order to breath. The ash itself caused air pollution that clearly affected the human respiratory system. (Boer & Sanders, 2002)

As mentioned above the ash cloud from the May 1980 eruption of Mt. Saint Helens circled the globe. With this came the spread of not only particulate mater, but also of SO2, which as mentioned before is reactive with water vapor in the air to produce H2SO4. These aerosols directly affected global weather patterns in the year following the eruption, though not on an extremely large scale. (Ritchie& Gates, 2001)

Overall the 1980 eruption of Mt. Saint Helens has been one of the most studied volcanic eruptions of our time. Through this study Mt. Saint Helens has given a more in depth understanding of the many aspects of volcano phenomena, but most importantly it has shed more light on air-blast explosions. Mt. Saint Helens is far from meeting her demise and in fact in late 2004 she awoke again with several small eruptions. No one is sure what the future of Mt. Saint Helens holds, but it is certain that she will erupt again, perhaps with a larger VEI than in 1980.