Volcanic eruptions have threatened to destroy Big Island communities since long before the keeping of written records.

Written and oral histories tell of Kilauea and Mauna Loa eruptions wiping out ancient and contemporary communities, erasing coastlines and adding hundreds of acres of land to the Big Island. A devastating 1790 blast powered by groundwater flashed into steam beneath the Halemaumau caldera, killed up to one third of Keoua’s warriors, perhaps several dozen or more, heading home to Puna after a battle with Kamehameha.

The destructive power of volcanoes and their molten hot flow have, over the decades, prompted government officials to take sometimes dramatic steps to divert nature away from populated areas.

Perhaps no reaction to avoid lava, though, tops the response to a Mauna Loa eruption that began in November 1935.

This aerial shot of the 1935 Mauna Loa eruption was taken by the U.S. Naval Air Service. The eruption sparked efforts to bomb the volcano to stop the flow of lava. USGS

For several weeks, a strong lava flow cascaded down the northeastern slopes of the world’s largest volcano, pooling in a natural depression. Thirty miles away, Thomas A. Jagger closely monitored the eruption’s progress from the Hawaiian Volcano Observatory; the flow was not unusual and appeared to be contained on the upper slopes.

But then on Dec. 24, the flow unexpectedly changed direction — and beelined toward Hilo.

Alarmed, Jagger dusted off a plan to divert Hawaii lava flows. Jagger wanted to blow craters in the main lava tube and change the lava’s direction. He was thinking mule trains and dynamite.

But Guido Giacometti, another HVO scientist, had another idea.

And that’s how the U.S. Army’s chief intelligence officer in Hawaii — Lt. Col George S. Patton – received the go-ahead on Christmas Day 1935 to bomb the hell out of the Mauna Loa eruption.

The hard-charging Patton gave the attack his best shot.

The future World War II war hero sent Army Air Force bombers from two squadrons based at Pearl Harbor’s Luke Field to the Big Island on Dec. 26, 1935. The next day, the 10 post-World War I era bombers dropped 20 bombs onto the exposed lava.

Five 500-pound bombs landed directly in the flow, blasting big craters in the lava tube that quickly filled. One bomber pilot reported the blasts splashed lava upward high enough to burn holes in his plane’s fabric-covered wings. Fourteen other bombs missed, including one dud that was not found until 1974.

Several days later, the Mauna Loa flow slowed, then stopped.

Jagger would later write the bombs were effective in altering that lava flow, although contemporary scientists tend not to agree.

HVO Slide Book 1, p. 2
Scientists look into the bright glow of Mauna Loa’s erupting vent in 1942. The eruption, occurring during World War II, was not publicized for fear that Japanese war planes would use it to navigate to the islands at night. USGS

Although the notion of bombing Kilauea would be a dud today,  throughout modern history, schemes have been cooked up to divert or stop lava flows from inundating valuable properties – towns, fishing harbors, villages clinging to the sides of active volcanoes.

When the terrain permits, constructing berms of rock, or dirt, or even large trees has been at least somewhat effective in the past. Flowing lava tends to follow a path of least resistance: racing down roads, blocked by rock walls. Roads and rock walls initially did control somewhat lava flows in Puna’s 1955 and 1960 eruptions. But they were soon overwhelmed by the unstoppable lava.

Among the more successful: Iceland marshaled national resources in 1973 to save Heimaey harbor, one of the country’s most valuable fishing ports, from a lava flow threatening to fill the harbor. Even with giant pumps flown in from the U.S. and heavy equipment piling massive berms, the effort took five months of pouring sea water onto the front of the lava flow.

The goal: cool and solidify a wall between the flowing lava and the harbor. The effort saved the harbor, though half the town was lost, and it succeeded only after flooding the advancing lava with 1.5 billion gallons of the Atlantic Ocean.

A similar Hawaii Volcanoes National Park attempt to use water to quench a lava flow advancing on the park’s Waha’ula Visitors Center failed, in part because the building was located miles from a ready source of nearly unlimited water.

A much earlier attempt to divert lava proved disastrous, as a 2006 “Volcano Watch” column notes. In 1669 on the flanks of Italy’s Mt. Etna, residents of Catania cut through a natural berm containing flowing lava that was headed directly toward their city.

The breach was successful, at first. Then the flow headed for the town of Paterno, which greatly upset that town’s residents. They prevented the Catania residents from keeping the breach clear; it eventually clogged and the flow swept through Catania.

The current Klauea eruption has already destroyed dozens of homes and is threatening the Puna Geothermal Venture power plant that supplies about 25 percent of the Big Island’s electric needs. But no government officials or anyone in the private sector is suggesting that an attempt should be made to divert the flow away from homes or businesses.

Currently, U.S. Geological Survey scientists are hands-off on lava-flow intervention, a 180-degree shift from the pre-WWII days of the legendary volcanologist who founded the Hawaiian Volcano Observatory in 1912.

18:20 Flow from vents near P. Haa
Mauna Loa continued to erupt for decades, including this 1984 event. Today, scientists are not attempting to divert lava flows. The recent eruption of Kilauea has destroyed more than three dozen structures, mostly homes. USGS

As the 1669 Etna diversion attempt revealed, “lava flow diversion is a complex legal, political, economic, technical, and cultural issue that must be decided by local and/or state government officials,” said Janet Babb, a geologist and public information officer with USGS based in Volcano.

The USGS, she said, “is not a regulatory agency, so we do not tell people what to do. We monitor volcanoes and provide information on hazards associated with volcanic activity.”

Perhaps the most powerful voices against lava flow intervention are those of Native Hawaiians who tend to believe a different force is also at work – one beyond human control.

“It’s Pele’s land,” says Kuulei Kanahele, a Hawaiian language instructor and volcano researcher for the Edith Kanaka’ole Foundation. “We as Hawaiian’s don’t believe in redirecting lava flows. Pele will flow where she needs to flow, and it’s heartbreaking to see this, people losing their homes, now.

“But these are modern times. Eruptions can happen where there are homes. It comes with the land.”

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