As the Mauna Loa eruption continues to lose vigor, geologists are unsure whether a second eruptive phase is coming.
Early yesterday, the U.S. Geological Survey’s Hawaiian Volcano Observatory reported that the effusion rate from Fissure 3 on Mauna Loa’s northeast flank had reduced, cutting off the supply of lava to the end of the main lava flow, and halting the advance of lava toward Daniel K. Inouye Highway.
This morning, that state of affairs continues. HVO Scientist in Charge Ken Hon reiterated that “there is not any threat to the highway anymore at all.”
Hon said the flow front, about 1.7 miles from the highway, will still glow and spread out over the next few days, but will not substantially move forward.
But Hon said the weakening of the volcanic activity does not necessarily indicate that the eruption is over. He said that somewhere between one third to one half of all eruptions in Mauna Loa’s Northeast Rift Zones undergo a transition from a highly effusive phase to a less effusive, but longer-lasting phase.
Hon said it seems clear that the highly effusive phase of this current eruption is winding down, but it is not yet clear whether a second phase will follow.
Should a second phase begin, Hon said it may be difficult for lava to leave the area around Fissure 3. Since yesterday, lava flows from the fissure have been sluggish and unable to make it further than a few kilometers from the fissure. With that lava cooling and crusting over, the fissure is now becoming surrounded by fairly high masses of cooler lava that new lava may not be able to surmount.
Hawaii County Civil Defense Administrator Talmadge Magno confirmed that the county no longer considers the highway to be in danger.
“I am happy to say that the threat to Daniel K. Inouye Highway is over,” Magno said, although he added that the county will continue to monitor the situation.
Mayor Mitch Roth said that, starting this weekend, commercial tour vehicles with a 15-passenger capacity or less will be allowed to traverse the Traffic Hazard Mitigation Route on Old Saddle Road.