Volcano Classification

Volcanoes are classified as extinct, dormant, or active. An extinct volcano is a volcano that is not now erupting and is not likely to erupt in the future. Kohala, shown above, has not erupted for 60,000 years and will probably not erupt again. Photograph by Steve Mattox, November 1993.

A dormant volcano is a volcano that is not now erupting but has erupted in historic time, since written records were kept (the last 200 years in Hawaii), and is likely to do so in the future. Mauna Kea, shown above, has not erupted in historic time but is expected to erupt again in the future. There is no precise distinction between an active and dormant volcano. Because some volcanoes remain inactive for thousands of years between eruptions, it can be difficult to distinguish between an active and a dormant volcano. Volcanologists at the Smithsonian Institution estimate that 1,500 volcanoes worldwide have the potential of erupting.

An active volcano is a volcano that is erupting or is expected to do so in the near future. Kilauea volcano has erupted from its summit and flank 63 times since 1790. This photo shows a flank eruption at Mauna Ulu. Kilauea has been erupting continuously since January 3, 1983. Photograph by Don Swanson, U.S. Geological Survey, October 20, 1969.

Five volcanoes make up the Island of Hawaii: Kohala, Hualalai, Mauna Kea, Mauna Loa, and Kilauea. The oldest volcano on the island is Kohala, which last erupted 60,000 years ago. It is difficult to know if Kohala is extinct or dormant because many Hawaiian volcanoes evolve through a rejuvenated stage. At present, Kohala is thought to be extinct, and the potential for a future eruption is low. Mauna Kea has erupted several times in the last 10,000 years. The most recent eruption was 3,500 years ago, long before the Polynesians arrived. Although Mauna Kea has not erupted in historical time, it is considered dormant volcano because it likely to erupt in the future. Hualalai is considered active because it last erupted in 1801. During an eruption about 2,650 years ago, lava flows covered most of the surface of the volcano. Hualalai has erupted about 200 times in the last 10,000 years. An eruption is highly probable in the next 200 years and could occur during the next few decades. Mauna Loa is an active volcano. The most recent eruption occurred in 1984. Most Mauna Loa eruptions begin at the summit. About half of these migrate to a rift zone. The 1984 eruption followed this pattern, with vents migrating into the northeast rift zone within a few hours after the eruption started. The eruption lasted 3 weeks, and lava flows advanced to within 4 miles (6 km) of Hilo. Mauna Loa eruptions commonly produce a large volume of lava, which can travel great distances in a short period of time. Kilauea is one of the world's most active volcanoes. The current eruption on the east rift zone began in January 1983. It is the largest-volume and most long-lived eruption of the east rift zone in historical time. The most recent eruptions on the southwest rift zone and summit occurred in 1974 and 1982, respectively.

Haleakala, on Maui, erupted in 1790 and is considered an active volcano. Haleakala is the only Hawaiian volcano not on the Island of Hawaii that has erupted in historical time. Crandell (1983) reported that Haleakala has erupted at least 10 times in the last 1,000 years. Aerial view of the south flank of Haleakala by Steve Mattox, March 18, 1996.

Volcanoes on the other islands also have the potential to erupt. However, none of these volcanoes have erupted in the last 10,000 years and are considered extinct. Youthful-looking features, such as Diamond Head and Punchbowl Craters on Oahu, serve as reminders for the potential of future eruptions. This photo shows part of the Koolau Range, the erosional remnant of one of the two shield volcanoes that make the island of Oahu. Kaneohe Bay is in the foreground. Photograph courtesy of U.S. Geological Survey, January 1981.

Click here for references about living with Hawaiian volcanoes.

Click here for activities about living with Hawaiian volcanoes.

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