Volcanoes as Natural Hazards
Volcanoes produce some of the most spectacular eruptions in the world, and also some of the most devastating natural disasters. While the ability of the geologists who study volcanoes to predict eruptions has increased quite a bit in the last few decades, we still have no real way to pinpoint the exact moment a mountain might explode. There are several ways, both immediate and long-term, that volcanoes pose a danger to humans.
1) Eruptive power (Mt St Helens)
When Mt. St. Helens erupted in May 1980, scientists estimated that the force of the blast was equal to 1,600 atomic bombs. The hot gases rocketing out from the volcano at over 600 m.p.h. killed every living thing for nearly 20 miles to the north of the cone, from a combination of heat and lack of oxygen.
1) Eruptive power (Mt St Helens)
When Mt. St. Helens erupted in May 1980, scientists estimated that the force of the blast was equal to 1,600 atomic bombs. The hot gases rocketing out from the volcano at over 600 m.p.h. killed every living thing for nearly 20 miles to the north of the cone, from a combination of heat and lack of oxygen.
2) Lahars and mudflows (Mt St Helens)
When Mt. St. Helens erupted in May, much of the winter snowpack still lay frozen atop numerous, more permanent glaciers. The snow and ice melted in an instant and combined with rock and ash to form giant mudflows, called 'lahars,' that channeled into the Toutle River, a tributary of the Columbia River.
When Mt. St. Helens erupted in May, much of the winter snowpack still lay frozen atop numerous, more permanent glaciers. The snow and ice melted in an instant and combined with rock and ash to form giant mudflows, called 'lahars,' that channeled into the Toutle River, a tributary of the Columbia River.
3) Ashfall (Mt St Helens)
The giant ash cloud produced during the volcanic eruption of Mt. St. Helens was carried to the east for hundreds of miles. As that ash began to fall, it produced a thick blanket across the land. This ash clogged air intakes on cars, airplanes, buildings, and other large machinery, mucked up rivers, and induced lung-related illnesses across the most-affected areas (including in Moscow!). Most people described the ashfall as like a blanket of snow, except that it did not melt, and caused problems for weeks.
4) Wildfire (Hawaii)
When volcanic eruptions spew lava into the surrounding vegetation, they can be responsible for starting forest fires. In 2011, the Napau Fire started in Hawaii Volcanoes National Park and burned more than 2,000 acres, a very large wildfire for someplace as tropical as Hawaii.
5) Global dimming (Pinatubo)
Mt. Pinatubo is a volcano in the Philippines that erupted in 1991. The volcanic ash plume rose straight through the stratosphere and was quickly distributed around the globe. While the lingering effect of this ash could not be seen with the naked eye, scientists were able to quantify a two-year period (1991-1993) where the amount of solar insolation received at Earth's surface was significantly lower than normal. This was associated with the extra Pinatubo ash in the atmosphere increasing the albedo of the upper atmosphere and reflecting more incoming solar radiation away from the Earth. They called this event 'global dimming.'
The giant ash cloud produced during the volcanic eruption of Mt. St. Helens was carried to the east for hundreds of miles. As that ash began to fall, it produced a thick blanket across the land. This ash clogged air intakes on cars, airplanes, buildings, and other large machinery, mucked up rivers, and induced lung-related illnesses across the most-affected areas (including in Moscow!). Most people described the ashfall as like a blanket of snow, except that it did not melt, and caused problems for weeks.
4) Wildfire (Hawaii)
When volcanic eruptions spew lava into the surrounding vegetation, they can be responsible for starting forest fires. In 2011, the Napau Fire started in Hawaii Volcanoes National Park and burned more than 2,000 acres, a very large wildfire for someplace as tropical as Hawaii.
5) Global dimming (Pinatubo)
Mt. Pinatubo is a volcano in the Philippines that erupted in 1991. The volcanic ash plume rose straight through the stratosphere and was quickly distributed around the globe. While the lingering effect of this ash could not be seen with the naked eye, scientists were able to quantify a two-year period (1991-1993) where the amount of solar insolation received at Earth's surface was significantly lower than normal. This was associated with the extra Pinatubo ash in the atmosphere increasing the albedo of the upper atmosphere and reflecting more incoming solar radiation away from the Earth. They called this event 'global dimming.'
Mitigating against the hazards posed by volcanoes is difficult, particularly because they are often found in coastal areas where most of the world's population lives. In the US, all known active volcanoes area monitored by the USGS. This monitoring likely saved tens of thousands of lives during the 1980 eruption of Mt. St. Helens, when USGS scientists successfully closed a large area around the mountain to the public.
Log in to BBLearn and complete "Assignment 7.1: Volcanic Hazards."
Log in to BBLearn and complete "Assignment 7.1: Volcanic Hazards."