Inflation of Mauna Loa says only a matter of time before it blows

HILO — Although Mauna Loa will not erupt this week, all signs point to an upcoming eruption in the relatively near future.

That was the conclusion of a presentation hosted by Hawaii Island Realtors and the Hawaii Island Chamber of Commerce Wednesday about the current status of the volcano and the hazards it presents.

Tina Neal, scientist in charge at the Hawaiian Volcano Observatory, said the volcano, which last erupted in 1984, has become “restless” in recent years and could feasibly erupt soon.

“It will erupt again,” Neal said. “So it behooves us as community leaders to prepare for that.”

Neal explained that the mountain — the largest volcano on Earth — is very active, having erupted 33 times since 1843, and presents a significantly greater risk to the island than its other volcanoes, such as the currently erupting Kilauea. Whereas Kilauea produces slow-moving, pahoehoe-forming lava, Mauna Loa has historically produced fast-moving flows that eventually form a‘a.

When Mauna Loa erupted in 1984, the lava reached within four miles of the Hilo city limits and emitted the same volume of lava in 20 minutes that Kilauea expels in a day.

A flow of lava from the summit Southwest Rift Zone of Mauna Loa can reach the South Kona coast within three hours, Neal said, as it did during an eruption in 1950. The town of Kailua-Kona is not in the path of Mauna Loa lava flows, as stated in an earlier version of this article, because it is shielded by Hualalai Volcano.

While Neal said the mountain will not erupt within the next two weeks, predicting the mountain’s activity beyond that time frame is difficult. However, because of increased seismic activity around the summit and caldera, the volcano’s status was upgraded from “normal” to “advisory” in 2015.

Magma has accumulated in subterranean reservoirs beneath Mauna Loa, Neal explained. Meanwhile, a GPS station at the mountain caldera has been pushed upward about 0.1 meters since 2012, as the mountain “inflates.”

“We are definitely moving towards an eruption,” Neal said.

In light of the probable future eruption, Big Island residents are encouraged to remain vigilant and prepared.

Barry Periatt, staff officer for Hawaii County Civil Defense, said emergency preparedness plans for lava flows are very similar to those residents should make for other disasters such as hurricanes, tsunamis and incoming ballistic missiles.

All emergency kits should include two weeks worth of supplies because of the island’s isolation from mainland supply chains. Furthermore, residents should make considerations for other personal items, pets, personal identification and documents, as well as where to rendezvous with family members.

“You need to consider that, if you evacuate, you should plan to find nothing when you return,” Periatt said.

Periatt added that Civil Defense has no plans to implement any lava diversion measures, because they would be extremely expensive and not certain to work because of the unpredictability of lava flows.

The most important preparedness measure, however, is to remain informed, Neal said. Subscribe to volcano updates on the U.S. Geological Survey website and on social media.

Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com