USGS: “As of 7:00 a.m. on December 12, Hawaiian Volcano Observatory geologists observed only residual incandescence and no lava movement in the fissure 3 vent on the Northeast Rift Zone of Mauna Loa. The channels below the vent appear drained of lava and no longer feed the main flow front.” (USGS image by F. Trusdell)

(BIVN) – The latest episode of volcanic activity on Mauna Loa is nearly paused, however scientists still see a few signs that suggest the eruption “may still be active”. Emergency officials say no communities are at risk.

Fissure 3, the dominant vent on the Northeast Rift Zone during the latest eruption, displayed only residual incandescence and no lava movement during a Monday morning overflight by the USGS Hawaiian Volcano Observatory. However, as the scientists were leaving, “the field crew heard small explosions accompanied by sprays of spatter from the west end of the fissure 3 (F3) vent.”

All lava flows associated with the eruption have stalled and are inactive. Volcanic tremor is no longer detectable, suggesting subsurface fluid movement has ceased.

Inflation continues at the summit and Northeast Rift Zone. “The significance of the continuing inflation while the flow field is inactive is not yet clear,” the USGS HVO wrote. “It is common for eruptions to wax and wane or pause completely, but none of the eight recorded eruptions from Mauna Loa’s Northeast Rift Zone returned to high eruption rates after those rates decreased significantly.”

The current Volcano Alert Level for Mauna Loa remains at WATCH / ORANGE.

From the USGS HVO report issued at 9:35 a.m. HST:

The Northeast Rift Zone eruption of Mauna Loa may still be active at the fissure 3 (F3) vent but all 2022 lava flows appear to be inactive.

As of 7:00 a.m. today, December 12, the Hawaiian Volcano Observatory overflight found only residual incandescence and no lava movement in the F3 vent; as they were leaving the field crew heard small explosions accompanied by sprays of spatter from the west end of the fissure 3 (F3) vent. The channels below the vent appear drained of lava and no longer feed the main flow front.

The inactive main flow front remains stalled about 1.7 mi (2.8 km) from the Daniel K. Inouye Highway (Saddle Road) when last measured the morning of December 10. The inactive main flow front still glows at a few spots at night and may inch northward very slowly as it continues to settle.

Sulfur dioxide (SO2) emission rates continue to be reduced; on December 10, the emission rate was approximately 2,000 tonnes per day (t/d). The Hawaii Interagency Vog Information Dashboard has detailed information about vog. Forecasts for the dispersion of vog can be found on the VMAP Vog Forecast Dashboard.

Tremor (a signal associated with subsurface fluid movement) is no longer detectable; summit and Northeast Rift Zone inflation continues.

The significance of the continuing inflation while the flow field is inactive is not yet clear; it is common for eruptions to wax and wane or pause completely, but none of the eight recorded eruptions from Mauna Loa’s Northeast Rift Zone returned to high eruption rates after those rates decreased significantly. Nevertheless, the Hawaiian Volcano Observatory continues to closely monitor the current activity.

There is no active lava within Moku’āweoweo caldera nor in either rift zone. Satellite imagery shows the entire 2022 flow field cooling and no longer active.