alaska volcano observatory

The United States, a volcanic hotspot, boasts 169 Holocene volcanoes, primarily in Alaska, Hawaii, and the Pacific Northwest. Hawaii's Volcanoes National Park, featuring Kilauea and Mauna Loa, attracts millions. The Cascade Range, including Mount St. Helens and Mount Rainier, offers dramatic landscapes and trails. Country with highest number of volcanoes, most active volcanoes, mount rainier, Hawaii Volcanoes National Park, volcano tourism

Mauna Loa is spewing sulfur dioxide and other volcanic gases. They form volcanic smog, or vog, when they mix with vapor, oxygen and dust in sunlight. As a result, state health officials are urging people to cut back on outdoor exercise and other activities that cause heavy breathing. Mauna Loa last erupted in 1984.