50 Fun Facts About Mauna Loa

What does the name Mauna Loa mean in Hawaiian?

Long Mountain is apt: the volcano stretches about 120 km, from the island's southern tip across the summit to the coast near Hilo.

Mauna Loa is one of how many volcanoes that form the Island of Hawaii?

Five volcanoes built the island, from oldest to youngest Kohala, Mauna Kea, Hualālai, Mauna Loa and Kīlauea; a sixth, Kamaʻehuakanaloa, is growing off the south-east coast but has yet to break the surface.

Mauna Loa holds which record among the world's volcanoes?

Largest active volcano by mass and volume is the title it keeps: bigger rivals mapped since, such as Pūhāhonu in the north-western Hawaiian chain, are ancient and long dead.

Mauna Loa is built almost entirely of which dark, iron-rich volcanic rock?

Basalt lava is unusually runny, so Mauna Loa's eruptions mostly pour out as flows instead of exploding like volcanoes with stickier magma.

What shape of volcanic edifice is Mauna Loa, built by very fluid lava?

A shield volcano is built from thin sheets of runny lava that travel far before they harden, which is why Mauna Loa is so broad and its slopes so gentle.

Why does Mauna Loa's base lie 8 km below the sea floor?

Its weight sagged the crust: the volcano's mass has pressed the sea floor into a deep bowl, so from true base to summit Mauna Loa stands about 17 km tall, nearly twice the height of Everest.

Roughly what share of the Island of Hawaii's land does Mauna Loa alone cover?

About 51 percent of the island is Mauna Loa, which is why its lava can threaten opposite coasts: flows reached the sea on the west side in 1950 and came close to Hilo, on the east, in 1984.

What is the name of Mauna Loa's summit caldera?

Mokuʻāweoweo formed when the summit collapsed, and it is where Mauna Loa's eruptions typically begin before lava breaks out lower on the flanks.

Mauna Loa's summit caldera is named after what kind of creature?

A fish: a red Hawaiian bigeye whose colour is said to resemble the glow of the crater's eruptive fires.

What supplies Mauna Loa's magma?

The Hawaii hotspot is a plume of hot rock rising from deep in the mantle; as the sea floor drifts across it, each volcano is eventually carried away from its magma supply and dies out.

For roughly how long is Mauna Loa thought to have been erupting?

About 700,000 years is the usual estimate: its first lavas erupted onto the sea floor between roughly 600,000 and a million years ago, so this giant is a geological youngster that had to grow extremely fast.

Kīlauea was long thought a mere satellite of Mauna Loa until lava chemistry showed the two have separate what?

Magma chambers are separate for each volcano, yet when one is busy the other has often gone quiet: Kīlauea slept from 1934 to 1952 while Mauna Loa erupted repeatedly.

What are the lava fountains that open a Mauna Loa eruption called?

Curtain of fire: the fountains jet in a row from a crack that can run a kilometre or more, like a glowing drape, before the eruption settles on a single vent.

During Mauna Loa's 1984 eruption, what volcanic haze blanketed much of the state of Hawaii?

Vog, short for volcanic smog, forms when sulphur dioxide from the vents reacts with sunlight, oxygen and moisture; laze is a different hazard, made where lava pours into the sea.

Mauna Loa's 2022 awakening gave the Island of Hawaii its first what since 1984?

Dual eruption: Kīlauea was already active next door, so the island had two volcanoes erupting at once. Both then went quiet within days of each other, a timing scientists called surprising and thought-provoking.

Which cross-island highway did Mauna Loa's 2022 lava flows threaten but never reach?

Saddle Road, which crosses the high saddle between Mauna Loa and Mauna Kea, escaped when the main flow stalled about 1.7 miles short as its lava supply drained away.

What halted Mauna Loa's 1984 flow before it could reach Hilo?

Channel breaks diverted the lava: natural levees upslope gave way and fed new side flows, so the tongue aimed at Hilo stagnated, and the eruption ended on 15 April.

What caused the loud explosions as Mauna Loa's 1984 lava crossed forest above Hilo?

Methane from scorched plants: lava cooks the vegetation it buries, and the gas seeps into hollows underground and explodes. In 1984 the blasts could be heard down in Hilo.

Mauna Loa's 1950 eruption sent lava to the ocean, 24 km away, in roughly how long?

About three hours was all it took: the lava cut the coast highway and swept through Hoʻokena-mauka, yet everyone in its path got out unharmed before it hit the sea in towering clouds of steam.

Which future general planned the 1935 bombing of Mauna Loa's lava to protect Hilo?

George S. Patton, then a lieutenant colonel in Hawaii, oversaw the Army raid of 27 December 1935; the lava stopped six days later, but whether the bombs deserve the credit is still disputed.

Why did the government gag the local press during Mauna Loa's 1942 eruption?

To deny Japanese bombers a beacon: with Hawaii under nightly blackout months after Pearl Harbor, officials feared the lava's glow could guide warplanes in, so the eruption went unreported.

Which Hawaiian word do geologists use worldwide for rough, clinkery lava like Mauna Loa's 1984 flows?

ʻAʻā flows carry a jumble of sharp, broken clinker on top of a dense molten core, which makes them brutal to walk across; smooth, ropy lava goes by another Hawaiian name, pāhoehoe.

What made Mauna Loa's eruption of 1872 to 1877 unusual?

It never left the summit: lava welled up in the caldera almost continuously for about 1,200 days, one of Hawaii's longest recorded eruptions, yet none of it threatened the towns below.

Where did Mauna Loa's one-day eruption of 1877 break out?

Underwater, just off the coast: people on the water saw the sea churning as if boiling and blocks of hot lava bobbing to the surface within a mile of the shore.

The Hawaiian snack brand that shares Mauna Loa's name is best known for which product?

Macadamia nuts are the Mauna Loa brand's business: it took the volcano's name because its first orchards were planted beneath the mountain in 1946.

Mauna Loa is one of 16 volcanoes on which watch-list drawn up by international volcanologists?

Decade Volcanoes were chosen in the 1990s, the UN's decade for disaster reduction, hence the name; each has a record of large eruptions close to where many people live.

Who founded the Hawaiian Volcano Observatory, which has monitored Mauna Loa since 1912?

Thomas A. Jaggar directed the observatory until 1940, and it was he who urged the Army to bomb the lava creeping toward Hilo in 1935, then declared the raid a success.

Which Army unit helped build the trail to Mauna Loa's summit in 1915?

The Buffalo Soldiers of the 25th Infantry, an African American regiment posted in Hawaii, cut the trail in 1915 so scientists could reach the summit; today's Mauna Loa Trail grew out of it.

Who led the first recorded ascent to Mauna Loa's summit in February 1794?

Archibald Menzies, botanist on the Vancouver expedition, reached the top on his third attempt and measured its height with a portable barometer, coming remarkably close to the modern figure.

Which Scottish botanist climbed to Mauna Loa's summit in January 1834?

David Douglas, the man behind the Douglas fir, spent a night at the top taking measurements; a few months later he was found dead in a pit trap for wild cattle on Mauna Kea.

Why was Mauna Loa chosen for the long-running record of atmospheric CO2?

Its air is remote and clean: high in mid-Pacific, far from cities, industry and vegetation, the station samples well-mixed background air, and readings are corrected for the volcano's own gas.

The graph of rising CO2 built from Mauna Loa readings is named after which scientist?

Charles David Keeling of Scripps began the measurements in March 1958 and ran them until his death in 2005; his curve gave the first clear evidence that CO2 in the air was climbing year after year.

Mauna Loa's daily CO2 reading first passed which milestone level in May 2013?

400 parts per million was passed on 9 May 2013; ten years later Pope Francis cited the Mauna Loa record in Laudate Deum, noting it had climbed to 423 by June 2023.

A telescope on Mauna Loa's northern slope tracks the outer atmosphere of which star?

The Sun is the target of the Mauna Loa Solar Observatory, whose coronagraph blocks the bright disc like an artificial eclipse, revealing the faint corona and the gas eruptions it hurls into space.

Which protected area covers Mauna Loa's summit and parts of its flanks?

Hawaii Volcanoes National Park has protected the summit since 1916, so no road reaches the top: seeing the caldera means a long, high-altitude hike.

Which Hawaiian goddess of volcanoes and fire is linked with Mauna Loa's eruptions?

Pele is called 'the earth-eating woman'; most stories place her home on neighbouring Kīlauea, but a few have her living in Mauna Loa's own summit caldera.

Why are no ice-age glacier deposits visible on Mauna Loa, unlike Mauna Kea?

Younger lava has buried them: Mauna Loa kept erupting, so any ice-age deposits lie under later flows, while long-quiet Mauna Kea still shows moraines from three glacial episodes.

Kīlauea's flank, wedged against Mauna Loa, is creeping seaward at roughly what rate?

About 10 cm a year sounds slow, but the strain builds: in 1975 the same flank lurched seaward several metres at once, setting off a magnitude 7 earthquake and a deadly tsunami.

A giant flank collapse over 100,000 years ago carved which bay on Mauna Loa's west side?

Kealakekua Bay is the scar of that landslide: its high cliffs mark where the flank gave way, and the debris may have sent a giant tsunami over Lānaʻi. Captain Cook was later killed on its shore.

Mauna Loa's lava flows so freely mainly because it is poor in which compound?

Silica is what makes magma sticky: lavas rich in it are thick and tend to erupt explosively, while Mauna Loa's low-silica melt pours out as fast-moving flows.

What did lava from Mauna Loa's 1926 eruption bury at Hoʻōpūloa?

A coastal village and its harbour were buried as a wall of lava crept through; a dozen houses and the church were lost, but no one was killed.

What long-term pattern has lava dating revealed in Mauna Loa's eruptions?

They swing between summit and rifts: for about a thousand years most lava poured from the summit, then roughly 700 years ago activity moved to the rift zones, and geologists have traced two such switches.

A NASA-funded crew spent a year sealed in a dome on Mauna Loa's slopes to rehearse life on which world?

Mars was the model: six volunteers lived in the HI-SEAS dome for a full year, ending in August 2016, on barren lava some 8,200 feet up that was picked for its Mars-like look.

Which Second World War battle site began as a volcano in Mauna Loa's island chain?

Midway began as a volcanic island like Hawaii's, then rode the drifting sea floor north-west, sinking and eroding until only a ring of coral reef was left at the surface.

In what way does neighbouring Mauna Kea outdo Mauna Loa?

Its summit is slightly higher, by little more than 100 feet, making Mauna Kea the highest point in Hawaii; it is dormant, though, and far smaller in bulk than its neighbour.

Coffee grown on the slopes of Mauna Loa and neighbouring Hualālai is sold under which famous district name?

Kona coffee comes from a narrow belt on the island's dry western side, where sunny mornings and cloudy, rainy afternoons suit the trees; only beans from the Kona districts may carry the name.

Which US Navy lieutenant led the exploring expedition that climbed Mauna Loa in December 1840?

Charles Wilkes had a gravity pendulum hauled to the top and camped for weeks on the crater rim in snow and gales; the ruined stone walls of his camp are still there.

Which US agency founded the Mauna Loa Observatory in 1956?

The Weather Bureau built it as a weather observatory on the north flank, about 3,400 m up; two years later it began the carbon dioxide record that made it famous, and NOAA runs it today.

On which flank of Mauna Loa did the main fissures of the 2022 eruption open?

Northeast: the eruption began in the summit caldera, then within hours shifted to the Northeast Rift Zone, the same side the 1984 lava took toward Hilo.

How did Mauna Loa's 2022 eruption interrupt the observatory's famous CO2 record?

Lava cut its road and power: flows buried about a mile of the access road and its power poles, so NOAA moved the measurements to a temporary site on Mauna Kea until July 2023.