The eruption that formed Mauna Ulu began on May 24, 1969 and continued until July 22, 1974.[1] At the time, this was the longest-lasting and most voluminous eruption on Kīlauea's flank in at least 2,200 years, lasting 1,774 days and producing 350 million cubic meters of lava.[1] Lava flowed down the sides of the feature and large lava fountains (Including one 539.5 meter high fountain) were witnessed.
https://en.wikipedia.org/wiki/Mauna_Ulu