Mauna Loa had not erupted since 1984—its longest quiet period in recorded history.
At approximately 11:30 p.m. HST November 27, lava broke to the surface within Moku‘āweoweo, the summit caldera on Mauna Loa, for the first time in 38 years.
The eruption started within Moku‘āweoweo,in Hawai‘i Volcanoes National Park, but it didn't stay there for long. HVO staff on an overflight at approximately 6:30 a.m. HST on November 28 confirmed that the summit eruption had ended and by that time, fissures at high elevations on the Northeast Rift Zone within Hawai‘i Volcanoes National Park were feeding lava flows upslope of the Mauna Loa Weather Observatory.
Several lava flows traveled in a northeast and east direction. Several fissures were active initially but the activity eventually focused at fissure 3, from which the longest and largest lava flow issued. This lava flow crossed the Mauna Loa Weather Observatory Road at approximately 8 p.m. November 28.
Lava flows extended 12 miles (19 km) from the vents in a north/northeast direction before the eruption ended on December 10. Lava flows came to within 1.7 miles (2.8 kilometers) of the Daniel K. Inouye Highway (Saddle Road).