Big Island residents await volcano's awakening

By Christie Wilson
Advertiser Neighbor Island Editor

With evidence that Mauna Loa is likely building toward another eruption after 18 years of relative quiet, scientists are holding a series of low-key yet purposeful meetings this week to let Big Island residents know what to expect if molten lava starts pouring down the mountainside.

Lava came within about three miles of Hilo during Mauna Loa's last eruption, March 25-April 15, 1984. Advertiser library photo • 1984

"People are hungry for knowledge. They want to know what's happening," said Darcy Bevens of Center for the Study of Active Volcanoes at the University of Hawai'i-Hilo. "Kilauea's been erupting since 1983, so people are more curious about Mauna Loa because it's so big and its eruptions are less constant."

But unlike some newcomers, kama'aina and longtime island residents are generally fatalistic about the inevitability of a big eruption.

"If it happens, it happens," said Helene Hale, 84. "You can't stop it."

She recalls watching a river of lava flow down Mauna Loa when the mountain erupted without warning in 1950. Hale, a state lawmaker representing the Puna district, had just built a house in South Kona with her husband. The lava got to within 300 yards of their home and cut off access to the property. It would be another six months before they could return.

"We knew we had built it on a volatile island with the possibility of lava. But there hadn't been an eruption since 1926. It's a chance you take on the Big Island," said Hale, who now lives below Leilani Estates in Puna, right on Kilauea's east rift zone.

Hawaiian Volcano Observatory scientists will be explaining their latest data on Mauna Loa at public meetings this week. Here's what they have been saying:

For the past eight years, the summit caldera at Mauna Loa was slowly subsiding and shrinking. But since late April or May, the summit area has been rising slightly and the caldera is widening. This suggests swelling of the magma reservoir within the volcano.

"The next eruption is a question of time, not if," said Donald Swanson, chief scientist at the observatory. He said that at this point, no one can predict when or where the volcano will erupt, how large it might be, how long it might last, or whether it might send lava into populated areas. Based on previous events, lava flows could travel down nearly any side of Mauna Loa, depending on where the vents open up.

This is the second-longest period without an eruption at Mauna Loa since 1843. The longest period without eruption lasted 25 years, between 1950 and 1975.

The scientists said the lack of tell-tale seismic activity that accompanied past eruptions means Mauna Loa likely will not erupt in the next few weeks. But it could happen in a matter of months, years, or even decades.

Observatory officials emphasize that Mauna Loa is not an explosive volcano. The past two eruptions, in 1975 and 1984, did no damage, although the 1950 event did destroy property in parts of South Kona. There have been no deaths from any of the 33 Mauna Loa eruptions since 1843, when written records start.

Mayor Harry Kim said he has been briefed by observatory staff about the changes at Mauna Loa but said no other preparations for an eruption are taking place. Kim said he is confident the county's Civil Defense system is ready for whatever happens, despite the unpredictable nature of volcanoes.

Kim was head of Hawai'i County Civil Defense during Mauna Loa's last eruption. There was no advance warning, and the lava flow advanced to within four miles of the outskirts of Hilo before the eruption stopped after 22 days.

During his 24 years as Civil Defense chief, Kim also dealt with Kilauea's Pu'u 'O'o-Kupa'ianaha eruption that has been ongoing since Jan. 3, 1983. Lava flows from that eruption have destroyed more than 180 structures in Lower Puna, mostly homes.

In 1950, the lava from an eruption of Mauna Loa needed less than four hours to reach the ocean. Advertiser library photo • 1950

Another difference between the two volcanoes is the volume of lava produced. The 1950 Mauna Loa eruption, which lasted 23 days, spilled 376 million cubic meters of lava. That's equivalent to about four years' output for the ongoing eruption of Kilauea, according to the observatory.

"If Mauna Loa erupts, it's a whole different ballgame," Kim said.

The high volume of output combined with Mauna Loa's steep topography means that lava flows can move far and fast. Flows from the 1950 eruption reached the coast in less than four hours. Arnold Okamura, deputy scientist in charge at the observatory, said it could take even less time, maybe even just two hours.

Bob Herkes, 71, who was elected this month to the state House for the district comprising Ka'u and South Kona, said he doubts residents understand the threat from a Mauna Loa eruption. He said evacuation time will be dangerously limited, particularly for areas such as Hawaiian Ocean View Estates, a relatively new community of 2,200 residents that was developed in Mauna Loa's southwest rift zone. It is about 40 miles from Kailua, Kona, and 70 miles from Hilo.

"A lot of people have been talking about it and the new people come in and ask questions. But none of us are the least bit concerned or worried about it," said Merri Magula, a 10-year resident of Hawaiian Ocean View Estates who works at the local Rancho Ace Hardware store. "The way I see it, it's just a big scare. You can't predict Mother Nature. She's going to do what she's going to do."

Magula said the enjoyment of living in a quiet, isolated, rural community such as Hawaiian Ocean View Estates outweighs any risk. "We all chose to live on a volcano. We all know what the consequences are," she said.

Swarms of earthquakes preceded both the 1975 and 1984 eruptions by a year and a half. Scientists were able to tell county officials the volcano would erupt two years out, but that was as precise as they could get, Okamura said.

"That doesn't mean we'll see the same thing before a new eruption, but we're sort of expecting that," Okamura said.

The actual areas that will be covered by flows and the warning time that can be given before lava reaches a specific area will not be known until an eruption begins.

"It depends on where you live. If you live in Hawaiian Ocean View Estates, which is right in the southwest rift of Mauna Loa, and start feeling a lot of earthquakes, I would not wait for anybody to tell you to evacuate. It could break out right in your back yard," Okamura said.

In a recent "Volcano Watch" report, the observatory said a worst-case scenario would be an eruption on the lower half of the southwest rift zone. "Such an event could unleash multiple flows that would cut Highway 11 (Hawai'i Belt Road) and enter residential areas in a few hours' time. The next worse-case scenario would be an eruption on the northeast rift zone that persisted for many months — long enough for flows to traverse the great distance to Hilo."

The report said the best-case scenario would be a summit eruption of Mauna Loa. "Such eruptions are limited to the summit caldera, Moku'aweoweo, and the uppermost regions of the two rift zones."

Of the 15 Mauna Loa eruptions during the past century, seven were summit events, according to the observatory.

The U.S. Geological Survey prepared a map of lava-flow hazard zones for the Big Island based on the locations of probable eruption sites, likely paths of lava flows, and how frequently lava has covered an area in the past.

The greatest hazard is in Zone 1; the least in Zone 9. South Kona and lands mauka of Hilo are in Zone 2. Hilo and Upper Puna are in Zone 3. The thin strips of land that make up the Kilauea and Mauna Loa rift zones are designated Zone 1.

"A good percentage of the island is not at risk of eruption," said Kim. "And Kilauea doesn't have much of an impact because the eruption zone is already covered with lava."

Still, he said, "everyone must be aware of this hazard and make an assessment of their own risk."

Advances in science and technology since the 1984 eruption have provided scientists with more tools to study the volcano. Geographic positioning system (GPS) receivers were installed on the summit and upper flanks of Mauna Loa in 1999 to detect changes in shape of the volcano that typically accompany underground movement of magma. The navigational system uses a network of 24 satellites to pinpoint locations on the Earth's surface. Data from the GPS receivers are what helped confirm that Mauna Loa was inflating.

Okamura, who has been at the observatory for 36 years, said that since 2000 the GPS receivers have been providing real-time measurements, allowing for quicker analysis of data, and that more of the instruments are being installed for wider coverage. Scientists also use electronic tiltmeters, highly sensitive instruments designed to detect minute changes in a volcano's shape.

Okamura said computer models were done to predict flow paths using contour maps, so that when lava breaks out from a particular area, officials will know immediately which communities may be affected.

He said the observatory wasn't trying to sound alarm bells by announcing that Mauna Loa is inflating. But it is a good time to remind Big Islanders, particularly those who arrived only recently, just what they could be facing.

"We don't want people to forget that it's an active volcano."

Advertiser staff writer Hugh Clark contributed to this report. Reach Christie Wilson at (808)244-4880 or cwilson@honoluluadvertiser.com.