The agency warned residents at risk from Mauna Loa lava flows should review their eruption preparations because of a recent spike in earthquakes at the summit of the volcano, which last erupted in 1984.
Mauna Loa, rising 13,679 feet (4,169 meters) above sea level, is the much larger neighbor to Kilauea volcano, which erupted in a residential neighborhood and destroyed 700 homes in 2018. Some of its slopes are much steeper than Kilauea's so when it erupts, its lava can flow much faster.
During a 1950 eruption, the mountain's lava traveled 15 miles (24 kilometers) to the ocean in less than three hours.
