Scientists had been on alert because of a recent spike in earthquakes at the summit of the volcano, which last erupted in 1984. [Source: ABC News]

Hawaii’s Mauna Loa, the world’s largest active volcano, has erupted for the first time in nearly four decades, causing volcanic ash and debris to fall nearby, authorities say.

Flows of lava remained contained within the summit caldera of Mauna Loa in the US island state, but the eruption could pose a threat to nearby residents should conditions change, the United States Geological Survey reported at 11:45 pm Sunday (09:45 GMT Monday), about 15 minutes after the eruption in Hawaii Volcanoes National Park .

The Geological Survey said the Hawaiian Volcano Observatory was in consultation with emergency management personnel and its staff would conduct an aerial reconnaissance over the 4,168-metre (13,674-foot) volcano as soon as possible.

Hawaii authorities said no evacuation orders have been given although the summit area and several roads in the region have been closed.