Mauna Loa: the largest volcano on Earth that almost never explodes
Mauna Loa is the most massive active volcano on the planet — about 75,000 cubic kilometres of rock, roughly half of Hawai'i Island. And in 111 eruptions in our database, it has never once erupted violently. It is simultaneously Earth's biggest subaerial volcano and one of its gentlest.
By VolcanoDB Research Team. Data: Smithsonian Global Volcanism Program (Mauna Loa, id 1071) and USGS Hawaiian Volcano Observatory. Live status verified Oct 28, 2026.
A mountain you can't see the size of
Stand on Mauna Loa and you don't feel like you're on the biggest volcano on Earth. The slopes are gentle — 2 to 10 degrees — and the summit sits at 4,170 m (13,681 ft), slightly lower than neighbouring Mauna Kea. That's the trick of a shield volcano: the bulk is spread out, not stacked up.
The number that matters is volume. USGS puts Mauna Loa at roughly 75,000 km³of rock. It rises about 9 km from the Pacific seafloor to its summit, and its sheer weight has pressed the ocean crust down several kilometres further. Its lava flows cover close to half of Hawai'i Island. For decades it was simply called the largest volcano in the world, full stop — until mapping after 2013 revealed even bigger, mostly-submerged shields nearby. If you want the three-way answer (tallest vs. most voluminous vs. most massive above water), our biggest volcanoes breakdown ranks Mauna Loa against Ojos del Salado and Pūhāhonu. The honest title for Mauna Loa is the largest active volcano that rises above sea level.
Biggest, and almost never violent
Here is the fact nothing else written about Mauna Loa leads with. We counted every size-rated eruption in its Smithsonian GVP record: 111 eruptions, and 102 of them — 92% — rate VEI 0 on the Volcanic Explosivity Index. Seven more are VEI 1. Exactly two reached VEI 2. In its entire recorded history, stretching back to around 8,050 BCE, Mauna Loa has never produced an eruption larger than VEI 2.
How Mauna Loa's 111 size-rated eruptions break down by Volcanic Explosivity Index. Select a bar to see what that size means.
Effusive — gentle lava flows with little to no explosion.
Of Mauna Loa's 111 size-rated eruptions on record, the most common was VEI 0 (102 of 111, 92%). It is overwhelmingly effusive, erupting gently at nearly the same small size again and again — classic shield-building behaviour. No eruption on record exceeded VEI 2.
Based on the Smithsonian GVP eruption record. This describes Mauna Loa's past eruptions only — it does not predict future activity. What is the VEI? · Most explosive volcanoes
To put that in scale: Vesuvius in AD 79 was a VEI 5, and Krakatoa in 1883 was a VEI 6 — thousands of times more explosive than anything Mauna Loa has ever done. The reason is chemistry. Mauna Loa erupts hot, low-silica, low-gas basalt. Gas escapes easily instead of building up to a blast, so the volcano pours out enormous volumes of fluid lava rather than exploding. Compare that to a page like Mont Pelée, whose record is dominated by lethal VEI 4s, and the shield-versus-stratovolcano difference stops being an abstraction. "Biggest" and "most dangerous" are two different volcanoes.
The 2022 eruption: 38 years of silence, then lava in three hours
Lava broke the surface inside Moku'āweoweo, Mauna Loa's summit caldera, at about 11:30 p.m. HST on November 27, 2022 — the first time it had erupted in 38 years, its longest pause in the recorded era (the previous eruption was in 1984). Within hours the activity migrated down the Northeast Rift Zone, where fissures opened inside Hawai'i Volcanoes National Park and began feeding lava downslope.
- Nov 27, 11:30 p.m. HST — eruption begins in the summit caldera.
- Nov 28 — activity shifts to the Northeast Rift Zone; fissure 3 becomes the main vent.
- Early December — longest flow advances within ~1.7 miles (2.7 km) of the Daniel K. Inouye Highway (Saddle Road), the island's main cross-island road.
- Dec 10 — the eruption ends; flows stop expanding by Dec 13.
Final flow field: longest flow ~19 km, ~43 km² covered, roughly 0.15 km³ of lava. Source: USGS Hawaiian Volcano Observatory.
The 2022 flows never reached a town, but the near-miss on Saddle Road is the point: Mauna Loa's lava is fast. In 1950, a Southwest Rift eruption sent lava 24 km to the sea in about three hours — the fastest Hawaiian flow on record. A volcano that never explodes can still cut an island in half.
Why Mauna Loa and Kilauea sit side by side
Two of the world's most active volcanoes share the same island, their summits only about 30 km apart. They sit over the same Hawaiian hotspot but tap separate shallow magma systems, which is why they can erupt independently — and occasionally seem to respond to each other. The contrast is stark: Kilauea is smaller, lower, and almost constantly active — its ongoing summit episodes have been fountaining lava on and off since December 2024. Mauna Loa is the giant that mostly sleeps, waking every few years to few decades.
| Mauna Loa | Kilauea | |
|---|---|---|
| Summit elevation | 4,170 m | 1,222 m |
| Volume | ~75,000 km³ | a small fraction of Mauna Loa |
| Eruption style | Rare, large-volume effusive | Near-continuous, smaller |
| Last eruption | 2022 | Ongoing (2024–present) |
| Max VEI on record | 2 | low (effusive) |
Both are tracked live on our active volcanoes tracker and the erupting-now dashboard, which pull current USGS alert levels. Mauna Loa's full data page lives at /1071/Mauna-Loa.
Seeing Mauna Loa
Mauna Loa sits inside Hawai'i Volcanoes National Park on the Big Island. The paved Mauna Loa Observatory Road climbs to about 11,150 ft, where the NOAA observatory (famous for its unbroken CO₂ record) sits on the north flank; from there a strenuous trail continues to the summit caldera. Most visitors pair a Mauna Loa viewpoint with Kilauea's far more accessible summit and lava sites a short drive away. Guided summit, stargazing and lava-viewing tours leave daily from Hilo and Kona.
Altitude is the real hazard here, not lava — the summit is above 13,000 ft and acclimatisation matters. Always check current conditions and alert status with the active volcanoes tracker before you go.
Compare guided hikes, crater walks, and day trips near Mauna Loa from local operators in Hawai'i, USA.
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Mauna Loa, quick answers
Is Mauna Loa the largest volcano in the world?
Mauna Loa is the largest active volcano on Earth — roughly 75,000 km³ of rock (USGS), rising about 9 km from the Pacific seafloor and making up roughly half of the Island of Hawai'i. It held the 'biggest volcano, period' title for decades. Research since 2013 has since found larger mostly-submerged shields, such as Pūhāhonu in the same Hawaiian chain, so Mauna Loa is best described as the largest volcano that rises above sea level.
When did Mauna Loa last erupt?
Mauna Loa last erupted from November 27 to December 13, 2022. Lava first broke the surface inside Moku'āweoweo, the summit caldera, around 11:30 p.m. HST on November 27 — its first eruption in 38 years — then shifted to the Northeast Rift Zone. The longest flow stretched about 19 km and came within roughly 1.7 miles of the Daniel K. Inouye Highway before activity stopped.
Is Mauna Loa more dangerous than Kilauea?
They're dangerous in different ways. Kilauea erupts far more often and does the most frequent property damage. Mauna Loa erupts rarely, but when it does it can push huge volumes of fast-moving basaltic lava toward populated areas — the 1950 Southwest Rift eruption reached the sea in about three hours. Neither explodes violently: both are shield volcanoes that produce fluid lava, not the ash-column blasts of a stratovolcano.
Is Mauna Loa active right now?
Yes. Mauna Loa is an active volcano currently at the USGS 'NORMAL' alert level — meaning no eruption is imminent, but it is monitored continuously by the Hawaiian Volcano Observatory. It last erupted in 2022 and has erupted on average every few years to few decades throughout its recorded history.
Continue exploring
Been to the summit, or watched the 2022 flows yourself? Tell us what the alert status and road closures actually looked like on the ground — we update these pages from reader reports and USGS data.