Mauna Loa eruption Day 15: Is it over?

For the first day since Mauna Loa began erupting more than two weeks ago at about 11:30 p.m. Nov. 27, the Hawaiian Volcano Observatory did not hold a news conference.

Scientists reported yesterday that the worldʻs largest active volcano no longer is producing lava that is moving outside and down the mountain.

Today, at 9:35 a.m., the volcano’s status report said the Northeast Rift Zone eruption of Mauna Loa may still be active at the main fissure 3 vent, but “all 2022 lava flows appear to be inactive.”

The Hawaiian Volcano Observatory responded that when an eruption is officially over is “sometimes a difficult question to answer.”

Because there was some active spatter observed today, the Mauna Loa eruption is not over yet.

“Generally, it might take some time of observance to determine if there is no longer lava being erupted,” according to the observatory.

During a 7 a.m overflight by observatory personnel, they found only residual incandescence ad no lava movement in the fissure 3 vent.

“As they were leaving, the field crew heard small explosions accompanied by sprays of spatter from the west end of the fissure 3 vent,” the status report said. “The channels below the vent appear drained of lava and no longer feed the main flow front.”

During the first 10 or so days of the eruption, the main flow was headed for the Daniel K. Inouye Highway (Saddle Road), threatening to cut off the primary east-west transportation corridor of the Big Island.

But now, the inactive main flow front remains stalled about 1.7 mi from 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. But with no new lava to feed the flow, it no longer is a threat to the highway.

There is inflation, or ground-surface swelling, which is caused by the accumulation of magma below ground. The observatory’s status report today said scientists do not know at this point the significance of the continuing inflation while the flow field is inactive.

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 Hawaiian Volcano Observatory will continue to closely monitor the current activity at Mauna Loa.  

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. 

Most recent eruption map: https://www.usgs.gov/media/images/most-recent-mauna-loa-northeast-rift-zone-eruption-map

Information on viewing the inactive flow front: https://hawaii-county-volcano-hazards-hawaiicountygis.hub.arcgis.com/