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After 25 years of slumber, Mauna Loa woke with a spectacular, but short-lived, eruption that began just before midnight on July 5. Lava fountains soon erupted from fissures extending across the length of Moku‘āweoweo, Mauna Loa's summit caldera, and into the upper ends of the volcano's northeast and southwest rift zones. After only 6 hours, the caldera and southwest rift zone activity ended, but fountains on the northwest rift zone continued to erupt until 7:30 p.m. on July 6, when all eruptive activity ceased. This July 6 photo shows eruptive fissures that opened along the Northeast Rift Zone of Mauna Loa and fed voluminous ‘A‘ā lava flows that quickly moved down the north flank of the volcano.
Mauna Loa 1975 eruption. Lava fountains up to 20 m (65 ft) high erupted from fissures on the north flank of the volcano early Sunday morning, July 6, 1975.