The active lava lake within Halemaumau Crater overflowing its levee, as painted by D. Howard Hitchcock in 1894. (Photograph by J.D. Griggs with permission of the Volcano House Hotel, owner of the original painting.)

Halemaumau Crater, as painted by D. Howard Hitchcock

For the past 200 years, Mauna Loa and Kilauea have tended to erupt on average every two or three years, placing them among the most frequently active volcanoes of the world. Some intervals of repose between eruptions at a given volcano have been much longer than its long-term average. The individual Kilauea eruptions recorded historically are in addition to the nearly continuous eruptive activity within or near Halemaumau Crater, extending throughout the 19th century and into the early 20th century.

Simultaneous eruption of both volcanoes has been rare except at times when Kilauea was continuously active before 1924. The only post-1924 occurrence of simultaneous eruption was in March 1984, when activity at both volcanoes overlapped for one day. Long repose intervals for one volcano correlate approximately with increased activity at the other. This general relation is imperfect but holds well for post-1924 eruptive activity. Between 1934 and 1952, only Mauna Loa was active and, between 1952 and 1974, only Kilauea was.

Since July 1950, Hawaiian eruptive activity has been dominated by frequent and sometimes prolonged eruptions at Kilauea, while only two short-lived eruptions have occurred at Mauna Loa

(July 1975 and March-April 1984). As of September 1986, Kilauea's eruption at Pu'u 'O'o, which began in January 1983, shows no signs of decline. Except for the nearly continuous eruptive activity at Halemaumau for a century before 1924, and at Mauna Loa summit between 1872 and 1877, the Pu'u 'O'o eruption has now become the longest lasting single Hawaiian eruption in recorded history.

A pattern of alternating dominant activity between Mauna Loa and Kilauea could imply that both volcanoes may alternately tap the same deep magma source. Whether this is so is a topic of scientific debate, because abundant chemical and physical evidence indicates that each volcano has its own shallow magma reservoir that operates independently of the other.

The average volume of lava erupted at Kilauea Volcano since 1956 is between 110 and 130 million cubic yards per year. In contrast, the average rate of lava output along the entire Hawaiian-Emperor Chain during its 70-million-year life is only about 20 million cubic yards per year. For reasons not yet understood, the rate of eruptive activity associated with the Hawaiian hot spot for the past few centuries appears exceptionally high relative to its long-term average.
High-fountaining episodes, Pu'u 'O'o eruption Brief high-fountaining episodes (shown by bars) alternated with longer intervals of low-level activity during the Pu'u 'O'o eruption. Width of bar indicates duration of high fountaining.

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Maintained by John Watson
Updated 05.01.97