STORY: The eruption ended the volcano's longest quiet period in recorded history.
The U.S. Geological Service has said the lava is contained within the summit and does not threaten Hawaiians living downslope for now. The service warned residents on Monday that volcanic gases and fine ash may drift their way.
Mauna Loa rises 13,679 feet (4,169 meters) above the Pacific Ocean, part of the chain of volcanoes that formed the islands of Hawaii.
It last erupted in March and April of 1984, sending a flow of lava within 5 miles (8.05 km) of Hilo, the island's largest city.