An Unexpected Journey: How Carbon Dioxide Fuels Erebus's Eternal Lava Lake
Antarctica's Mount Erebus, the southernmost active volcano on Earth, is home to a rare and mesmerizing sight: a persistent lava lake. Discover how COâ‚‚ enables this geological wonder.
The Volcano That Shouldn't Be
Imagine a volcano at the end of the world, where fire meets ice in a spectacular display of nature's contradictions. This is Mount Erebus, Antarctica's only active volcano. Unlike the typical explosive volcanoes of the Pacific Rim, Erebus boasts a rare, persistent lava lake—a bubbling cauldron of molten rock that has captivated scientists for generations 1 3 .
What makes Erebus truly extraordinary is not just its location but how it works. While most well-known volcanoes are powered by water-rich magmas that often get trapped deep underground, Erebus plays by different rules. Recent research has revealed that its secret weapon is carbon dioxide (COâ‚‚), which acts as a deep-earth elevator, allowing magma to travel continuously from the Earth's mantle to the surface in a journey that defies conventional volcanic behavior 1 3 4 .
This discovery "expands our understanding of the sources and transport of diverse types of magma and volatile gases to the surface," according to geophysicist Phil Wannamaker of the University of Utah 1 .
Location
Ross Island, Antarctica
Lava Lake
Persistent since at least 1972
Key Volatile
Carbon Dioxide (COâ‚‚)
Fire and Ice: The Two Faces of Volcanism
To appreciate Erebus's uniqueness, we must first understand the fundamental difference between the two major families of volcanoes:
Water-Dominated Arc Volcanoes
- Found at: tectonic plate boundaries where ocean crust sinks beneath continental crust
- Dominant volatile: Hâ‚‚O from dehydrated ocean crust and sediments
- Behavior: As magma rises and pressure decreases, water flashes into steam, often causing explosive eruptions
- Magma transport: Typically stalls about 3 miles (5 kilometers) deep, freezing in place rather than reaching the surface 1
- Examples: Mount St. Helens, Mount Fuji
COâ‚‚-Dominated Rift Volcanoes
- Found in: continental rift zones where Earth's crust is being pulled apart
- Dominant volatile: COâ‚‚ from much older recycling of ocean crust and sediments
- Behavior: Magma rises more peacefully, often forming persistent lava lakes
- Magma transport: Reaches the surface relatively uninterrupted 1 4
- Examples: Mount Erebus, Nyiragongo in East Africa
Volcano Type Comparison
| Feature | Hâ‚‚O-Dominated Arc Volcanoes | COâ‚‚-Dominated Rift Volcanoes |
|---|---|---|
| Tectonic Setting | Subduction zones | Continental rift zones |
| Dominant Volatile | Water (Hâ‚‚O) | Carbon dioxide (COâ‚‚) |
| Eruption Style | Often explosive | Generally more peaceful |
| Magma Stalling | Common at ~5 km depth | Rare; reaches surface |
| Surface Features | Craters, domes | Persistent lava lakes |
This fundamental difference in volatile content creates dramatically different volcanic personalities. While water-rich volcanoes tend to be explosive and unpredictable, COâ‚‚-rich volcanoes like Erebus can maintain steady, long-lived activity with pools of lava that remain liquid for years or even decades.
The Geophysical Detective Work: Seeing Through Rock
Unraveling Erebus's secrets required peering deep into the Earth—a task impossible with conventional means. You can't drill deep enough to sample magma chambers, and the lack of deep-seated earthquakes around Erebus made seismic imaging challenging 4 . The solution? Magnetotelluric (MT) sounding, a sophisticated geophysical technique that uses natural electromagnetic waves to create what's essentially a CT scan of the Earth 1 4 .
How Magnetotelluric Sounding Works
Natural Energy Sources
The sun and lightning bolts create electromagnetic waves that travel through the Earth's interior 1
Penetration and Scattering
These waves pass through Earth's interior, traveling at different speeds depending on how well materials conduct electricity
Detection
Sophisticated "volt meters" at the surface measure the returning signals
Image Creation
Computer programs assemble patterns from multiple stations to create detailed images of Earth's crust and mantle
This technique is particularly effective for detecting magma because molten rock is highly conductive compared to surrounding solid rock, making it stand out clearly in MT images 1 .
The Scientist's Toolkit for Magnetotelluric Research
| Tool/Technique | Function | Application at Erebus |
|---|---|---|
| Magnetotelluric (MT) Sounding | Uses natural electromagnetic waves to image subsurface electrical resistivity | Mapping magma pathways from mantle to surface |
| Impedance Phase Tensor Analysis | Distinguishes shallow geological changes from deeper structural zones | Identifying regions of crustal-scale magmatic activity |
| 3D Nonlinear Inversion | Computer algorithm that converts MT measurements into detailed resistivity models | Creating 3D images of the volcanic system including topography and bathymetry |
| Topography & Bathymetry Inclusion | Accounts for effects of surface features (mountains) and underwater terrain | Preventing misinterpretation of data, especially important with Erebus's prominent edifice |
The Unexpected Discovery: A Magmatic Detour
When researchers analyzed their magnetotelluric data, they discovered something completely unexpected: a continuous pathway of molten rock extending from the upper mantle to the surface, but with a surprising twist 1 3 4 .
The MT data revealed a steep conduit of low electrical resistivity originating in the upper mantle—the magma source. But instead of rising straight to the surface, this conduit takes a pronounced lateral turn in the deep crust before eventually reaching shallower magmatic storage and the summit lava lake 1 4 .
This lateral turn represents what scientists call a structural 'fault-valve' that controls the episodic flow of magma and COâ‚‚ gases. This valve replenishes and heats the high-level phonolite magma evolution chamber 3 4 . The valve is likely formed by intersecting north-south and east-west faults, which provide the magma's path to the surface 1 .
Key Findings from the Magnetotelluric Study
| Feature Identified | Description | Significance |
|---|---|---|
| Upper Mantle Conduit | Steep pathway of low electrical resistivity originating in magma source | Confirmed deep mantle source for Erebus magmas |
| Deep Crustal Lateral Turn | Pronounced sideways turn of magma pathway in deep crust | Revealed unexpected structural control on magma ascent |
| Fault-Valve Mechanism | Structural feature controlling episodic magma and gas flow | Explains how magma transport is regulated before reaching surface |
| Continuous Resistivity Anomaly | Unbroken conductive pathway from mantle to shallow crust | Shows COâ‚‚-rich magma doesn't stall like Hâ‚‚O-rich magma |
| Young Phonolitic Vents Correlation | Warm phase tensor ellipses southwest of summit | Matches area of younger volcanic activity and flows |
Research Insight
This discovery provided the missing piece in understanding how Erebus maintains its persistent lava lake. Unlike Hâ‚‚O-rich arc volcanoes where magma gets stuck deep underground, the COâ‚‚-dominated system at Erebus allows continuous flow to the surface, with the fault-valve system regulating the pace of ascent 4 .
Beyond the Lava: Erebus's Hidden Worlds and Global Significance
The implications of Erebus's CO₂-driven volcanic system extend far beyond explaining its lava lake. The volcano hosts astonishing hidden ecosystems within its volcanic ice caves 5 . Here, where geothermal heat meets ice, temperatures can reach a balmy 77°F (25°C)—a staggering contrast to the brutal cold above, where winter temperatures can drop below -100°F (-73°C) 5 .
Within these caves, researchers have discovered thriving microbial communities featuring bacteria and fungi with no close relatives elsewhere on Earth 5 . These organisms survive through chemosynthesis—deriving energy from chemical reactions rather than sunlight, using volcanic gases as their energy source 5 .
The ecosystem is so alien that NASA uses it as a test environment for potential missions to the icy moons of Jupiter and Saturn, where similar life might exist in subsurface oceans 5 .
Climate Implications
COâ‚‚-dominated volcanoes like Erebus "contribute enormous amounts of COâ‚‚ to the global exosphere budget, with climate-forcing level increases of atmospheric concentrations documented several times during Earth's history" 4 .
Resource Potential
Such volcanoes "are important hosts for essential mineral deposits such as rare earths, increasingly important for societies future resource needs" 1 .
The Future of Volcanic Discovery
The story of Erebus reminds us that our planet still holds profound mysteries waiting to be uncovered. The clever use of magnetotelluric sounding—essentially listening to the natural electromagnetic whispers of the Earth—has revealed a hidden world where carbon dioxide, often cast as a villain in climate discussions, plays the heroic role of magma elevator.
Mount Erebus at a Glance
- Elevation 3,794 m (12,448 ft)
- Location Ross Island, Antarctica
- Volcano Type Stratovolcano
- Last Eruption Ongoing
- Lava Lake Persistent since 1972
- Key Volatile Carbon Dioxide
Research Methods
Magnetotelluric Sounding
Primary imaging techniqueField Deployment
129 sites across Ross Island3D Inversion Modeling
Data analysis techniqueKey Terms
Similar Volcanoes
Nyiragongo
Democratic Republic of Congo