September 29, 1919 Eruption of Mauna Loa

The Mauna Loa volcano eruption of September 28 poured lava into the sea at Alika on the Kona coast on September 30, generating unusual wave activity at times. There was not an accompanying earthquake nor could the velocity of the lava flow generate a tsunami. A possible explanation would be the sudden collapse of the 1.5-day accumulations of lava at or beyond the shoreline (Reference #236).

The eruption had begun 26 September at the summit of Mauna Loa, but vents on the south rift opened about midnight of the 28th-29th. One of the lava flows reached the sea at Alika, on the Kona coast, at 04:30 Saturday, 30 September. The discharge of lava into the sea was considerable, and three days later the flow had built a delta into the sea (Reference #80).

1919, Septetmber-October. On September 26, the Mauna Loa volcano, which had been dormant since June 1916, revived. The eruption began at a height of 3300 m, that is, 600 m below the top of the volcano and was observed by Jagger from 18:00 on the 26th to 3:00 on the 27th. After two days of quiet, the eruption resumed at 2:00 on the 29th, but now at a height of 2300 m. A thick flow of lava issued from this lower crater. Less than 24 hours later, it filled up all irregularities of the relief, drove a road through the forest and reached the sea side approximately 28 km (15 miles) from the crater. For 10 days, the flow poured into the water, sometimes generating local tidal waves. Then the eruption began to subside, although volcanic activity was still noticeable on October 23 (Reference #415).