Volcanoes

In 2005, the U.S. Geological Survey (USGS) released a comprehensive review that the United States and its territories contain 169 geologically active volcanoes, 54 of which are a high threat to public safety: “As populations increase, areas near volcanoes are being developed and aviation routes are increasing. As a result, more people and property are at risk from volcanic activity. Future eruptions can affect hundreds of thousands of people.” The report established a framework for a National Volcano Early Warning System.

Worldwide, more than 50 volcanoes erupt each year. Approximately 500 million people on Earth live close to volcanoes. In the past 100 years, nearly 100,000 people have been killed by volcanic eruptions. Densely populated countries with many active volcanoes, such as Mexico, Japan, the Philippines, and Indonesia, are particularly vulnerable. When volcanic hazard mapping, monitoring, forecasting and early warning, and emergency plans are in place, it may be possible to evacuate populations and save lives before disaster strikes. However, a sudden event will be a disaster in the absence of mitigation and preparedness, despite monitoring and warning preparations, such as Mount St. Helens in Washington State in 1980.

A volcanic hazard refers to any possible volcanic activity. A volcanic risk is any potential loss or damage as a result of the volcanic hazard. Risk also includes a population's vulnerability. The increased number of deaths is not due to increased volcanism, but rather, to an increase in the population near those active volcanoes. The volcanoes that surround Mexico City have shown signs of increased activity. If a sudden eruption took place, a catastrophe could result; for example, El Popo is located within 60 miles of more than 20 million people in the Mexico City region.

About two-thirds of 1,500 active volcanoes on Earth are located in the Ring of Fire that surrounds the Pacific Ocean. Particularly, the Cascade Range, with more than a dozen active volcanoes, is close to various critical infrastructure, air routes, and populated areas in Washington, Oregon, and California. Outside the Ring of Fire, Mauna Loa in Hawaii is the world's largest active volcano. In western Central America, Nicaragua, Guatemala, Costa Rica, the Caribbean, Colombia, Ecuador, and along the Andes, Peru, and Chile, the population is exposed to volcanic activity. Europe has a number of active volcanoes, including Santorini (Greece), Surtsey and Heimaey (Iceland), Pompeii and Etna (Italy), which have erupted many times.

The volcanic molten (magma) materials (lava flow and ash) ejected from volcanoes during eruptions are extremely hot (around 1,830 degrees Fahrenheit). Such high-temperature lava flows burn and damage any object in their path. Volcanic ash is a powdery material that can affect people hundreds of miles away from a volcano. In 1980, when Mount St. Helens erupted, it killed 58 people and caused more than $1 billion in property damage. Hot lava created fires, many buildings [Page 762]were buried, and more than 200 houses were destroyed. The eruption of Mount Asame in 1783, which is called Japan's Pompeii, killed 1,400 people in a single day. In 1902, a lava flow from Mount Pelée in the West Indies killed 30,000 people in the nearby town of St. Pierre in a matter of minutes. After the Mount Unzen (Japan) eruption of 1991, hot ashfall and large rock fragments killed 43 people and burned schools and homes. The 1992 eruption of Mount Pinatubo in the Philippines caused 932 deaths, and more than 250,000 people had to be evacuated. More than 100,000 houses and several hospitals and schools were destroyed and damaged. Lahars (a lava pyroclastic flow, mud, and water mixture) can move down valleys to great distances from the volcano. In 1985, the eruption of the Nevado del Ruiz volcano in Colombia sent mud and ash flows down into the valley below where people were sleeping. Within 15 minutes, the city was buried under a 30-foot blanket of hot ash and mud, and more than 23,000 people perished.

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