1. Volcanic eruptions are one of Earth’s most dramatic and violent agents of change. Not only can powerful explosive eruptions drastically alter land and water for tens of kilometers around a volcano, but tiny liquid droplets of sulfuric acid erupted into the stratosphere can change our planet’s climate temporarily. Eruptions often force people living near volcanoes to abandon their land and homes, sometimes forever
2. Extreme heat from lava entering the sea rapidly boils and vaporizes seawater, leading to a series of chemical reactions. The boiling and reactions produce a large white plume, locally known as lava haze or laze, which contains a mixture of hydrochloric acid (HCl) and concentrated seawater. This is a short-lived local phenomenon that only affects people or vegetation directly under the plume.
The hydrochloric acid (HCl) comes from the breakdown of seawater-derived chlorides during sudden boiling. Because the lava is largely degassed by the time it reaches the sea, any HCL coming from it is insignificant by comparison. Analyzed samples of the plume show that is is a brine with a salinity of about 2.3 times that of seawater and a pH of 1.5-2.0.
3. Many stratovolcanoes have a plumbing system of hot acid water that progressively breaks down hard rock to soft, clay-rich material. The volcano is gradually weakened, and large parts may suddenly fail. Resulting water-rich landslides are especially dangerous because they can occur without any volcanic or seismic warning.
The risk of mudflows formed this way is especially high along rivers downstream from Mount Rainier, because of the large population on floodplains, the huge weakened edifice of the volcano, and a long history of large flows that occurred when the volcano was otherwise dormant.
4. At several volcanoes around the world, carbon dioxide gas has accumulated in the soil associated with certain volcanoes in concentrations sufficient to kill vegetation, or has collected in low areas and suffocated animals.
One USGS report states that, at Mammoth Mountain in California, “Carbon dioxide has killed about 100 acres of trees since 1989, and visitors to the area have occasionally suffered symptoms of asphyxiation when entering cabins or below-ground excavations.” USGS scientist conclude that the potentially lethal gas is escaping from a body of magma buried beneath the mountain.
5. There are about 65 volcanoes in the United States that scientists consider active. Most of these are located in Alaska, where eruptions occur virtually every year. Others are located throughout the west and in Hawaii (see our Volcano Activity Map for their locations). Kilauea volcano in Hawaii is one of the most active volcanoes on Earth. It has been erupting almost continuously since 1983
6. There are about 1500 potentially active volcanoes worldwide, aside from the continuous belt of volcanoes on the ocean floor. About 500 of these have erupted in historical time. Many of these are located along the Pacific Rim in what is known as the “Ring of Fire.” In the U.S., volcanoes in the Cascade Range and Alaska (Aleutian volcanic chain) are part of the Ring, while Hawaiian volcanoes form over a “hot spot” near the center of the Ring.
Western State Writers Spring 2009 