Volcano Minute — The 1926 eruption of Mauna Loa occurred 100 years ago this year

Aloha, it's your weekly Volcano Minute, brought to you by the USGS Hawaiian Volcano Observatory. 

This past April marked one hundred years since Mauna Loa’s 1926 Southwest Rift Zone eruption — an eruption remembered for its dramatic lava flows, community impacts, and scientific firsts. 

The eruption began in the early morning hours of April 10th, following strong earthquakes felt across the island. Lava first broke out near the summit, lighting up the sky. Within days, activity had migrated into the Southwest Rift Zone, where a fast‑moving ‘a‘ā flow drew large crowds as it crossed Government Road — what we know today as Highway 11. 

Downslope, concerns grew for Ho‘ōpūloa, a small coastal fishing village. As the lava flow approached, residents removed belongings and made offerings to Pele. Lava reached the village before dawn on April 18th. By mid‑morning, Ho‘ōpūloa was completely destroyed, displacing more than 40 people. 

The 1926 eruption of Mauna Loa also marked the first time aerial photographs were taken of active Hawaiian lava flows, by the U.S. Army Air Corp 11th Photo Section based at Pearl Harbor. Today aerial surveys are a regular part of the USGS Hawaiian Volcano Observatory’s eruption response but this technique was revolutionary in 1926.  Police also coordinated traffic and viewing areas in 1926, setting the groundwork for how crowds are managed at eruptions today. 

A century later, Mauna Loa is currently at alert level normal and scientists continue to closely monitor the slow refilling of the magma storage system beneath the summit following the 2022 eruption 

Mahalo for listening, I’m Katie Mulliken and this was your weekly volcano minute brought to you by the USGS Hawaiian Volcano Observatory.