Emergency Preparedness and Response

Volcanoes

Severe weather events, such as volcanic eruptions, occur unexpectedly and often pose major health threats. Occasionally, volcanoes build up pressure and must release this pressure through eruptions. Preparing for a volcanic eruption can be extremely difficult as the warning signs from volcanoes do not guarantee that there will be an eruption. The direct danger area around a volcano covers approximately a 20-mile radius. Volcanic eruptions are destructive and hazardous to homes as they can contaminate water supplies, damage machinery, and cause power outages. Eruptions also create smog and harmful gases that reduce visibility and irritate the skin, eyes, nose, and throat. Common volcanic gases like carbon dioxide, sulfur dioxide, and water vapor can cause breathing problems for anyone exposed, especially for people with asthma and other respiratory issues. Volcanic eruptions can also cause other extreme weather events such as floods, mudslides, and wildfires.

Definition

A volcano is a cone-shaped mountain or hill that opens into the Earth’s surface and allows magma (hot liquid and semi-liquid rock located underground), volcanic ash, and gases to escape. Volcanoes act as safety valves that release pressure built up inside the Earth. When pressure builds up, eruptions occur. When magma, volcanic ash, and gases escape, it is referred to as a volcanic eruption. Volcanic eruptions are expulsions that can range from low to high explosivity, depending on the composition of the magma. When the magma is thin and runny, gases escape more easily and flow out of the volcano. Volcanic eruptions occur most often along the Pacific Rim, in the “Ring of Fire.” The Ring of Fire is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. Eruptions happen when rocks slowly melt due to heat deep within the Earth; the thick, flowing magma collects in chambers as it rises and eventually pushes through vents, leaking out of the ground. Magma shoots up through the volcano, and flows down the sides as lava. Lava can be as hot as 2,200° F, appearing to glow red or white as it flows.

Susceptible Populations

Volcanoes are located all over the world, and volcanic eruptions can occur at any point in time. Information on volcanic eruptions can be found using websites, news articles, and mobile apps. The lists below can be used to identify volcanoes in your area.

Holocene Volcano List [List of Global Volcanoes] 
The National Museum of Natural History lists volcanoes of the world and their subregions. [url; Smithsonian Institution; 2024]

Volcano Hazards Program [List of U.S. Volcanoes] 
The U.S. Geological Survey provides a list of volcanoes located throughout the United States and its territories. [url; USGS]

Categorization of Volcanoes and Their Activity

A volcano may be categorized as active, dormant, or extinct.

  • An active volcano is one with a recent history of eruptions and that is likely to erupt again in the near future.
  • A dormant volcano is one that has not erupted for a very long time but may erupt in the distant future.
  • An extinct volcano is one that has not erupted in human history and is not expected to erupt in the future.

When a volcano erupts, the eruption may be described as effusive or explosive.

  • An effusive eruption involves the formation of lava flows by magma that can be gentle and quiet but still have the potential to ignite fires and form harmful gas clouds.
  • An explosive eruption involves ash, gas, and lava being sent high up into the atmosphere along with volcanic rocks and mud.

Federal Programs

Per their website, the U.S. Department of the Interior Geological Survey’s Volcano Hazards Program “provides situational awareness by:

  • Issuing authoritative forecasts, warnings, and status updates of volcanic activity;
  • Investigating and rectifying reports of unrest and eruption that are false or misleading;
  • Providing access to volcanic information and real-time data to the public via websites, social media, and subscription services;
  • Participating in targeted volcano-hazard education and planning activities.”

Understanding Recent Volcanic Events

The articles below describe recent volcanic eruptions and provide explanations on their occurrences.

Mauna Loa Eruption Teaches Us More About Volcanoes, Says SU Lava Project Scientist
A professor at Syracuse University provides detailed information about Mauna Loa, the largest active volcano on our planet, and its most recent eruption. [url; Syracuse University News, 2022]

Volcano Experts Explain the ‘Very Unusual’ Eruption Near Tonga and the ‘Tsunami Genesis’ impact on California
Volcano experts explain the eruption of Hunga-Tonga-Hunga-Ha’apai, an underwater volcano near the Pacific Nation of Tonga and the tsunami that followed afterwards. [url; CapRadio, 2022]

 

Latest page update: September 10, 2024.