Volcanes
Lava Academy Podcast: The Sleeping Giant Beneath the Ice: Öræfajökull
Helga Þorvaldsdóttir is a PhD candidate in volcanology and petrology, studying one of Iceland’s most powerful and overlooked volcanoes: Öræfajökull.
A lifelong science lover, Helga first became fascinated with geology in high school. What started as curiosity about nature soon became a passion for understanding volcanoes from the inside out. Helga is also a science educator, you can follow her Instagram account Geology With Helga.
Her current focus? Exploring the explosive history and inner workings of Öræfajökull, Iceland’s highest peak and one of the country’s most dangerous volcanic systems.
What Is Öræfajökull?
Öræfajökull is a glacier-covered volcano in southeast Iceland, sitting beneath part of Vatnajökull, Europe’s largest glacier.
Unlike more famous Icelandic volcanoes such as Katla, Hekla, or Eyjafjallajökull, Öræfajökull does not erupt often. During historic time, it has erupted only twice:
1362
1727
That long silence is part of what makes it so easy to overlook. But according to Helga, it is also one of the reasons it deserves more attention.
Iceland’s Most Overlooked Giant
Öræfajökull is not located on Iceland’s main active rift zone, where many of the country’s earthquakes and eruptions occur. It sits farther away, making it quieter, less obvious, and harder to monitor.
But quiet does not mean harmless.
Helga describes Öræfajökull as “silent and sneaky.” It is a volcano with a dramatic past, a complex structure, and a glacier on top—making any future activity especially challenging to understand.
The 1362 Öræfajökull Eruption
The 1362 eruption was one of the most catastrophic eruptions in Icelandic history.
Before the eruption, the region was known as a green, peaceful farming area. Helga compares it to “the Shire”—lush, settled, and full of life.
Then the volcano erupted.
The eruption was so devastating that the area became a wasteland for decades. It even changed the name of the region and volcano. Before the eruption, Öræfajökull was known as Knappafellsjökull. Afterward, the surrounding area became associated with the word Öræfi, meaning wasteland or ruined land.
A Landscape Transformed
The eruption completely changed the region.
The main impacts included:
Ashfall covering the land
Glacial outburst floods rushing from the ice
Pyroclastic density currents sweeping down the volcano
Fine ash filling the air
Farmland becoming uninhabitable
Helga explains that after the eruption, the area would have looked like a pale, dusty desert. Instead of Iceland’s familiar black volcanic sands, the landscape was coated in light-colored ash and tephra.
For 40 to 50 years, the area was essentially uninhabitable.
What Made the Eruption So Dangerous?
The 1362 eruption was not a gentle lava flow like many of the recent eruptions on the Reykjanes Peninsula.
It was an explosive eruption.
That difference comes down largely to magma chemistry. Iceland is famous for basaltic lava—hot, runny, and often seen in flowing lava eruptions. But Öræfajökull can produce more silica-rich magma, which is thicker, stickier, and more explosive.
Instead of flowing out as lava, the magma in 1362 fragmented violently into ash.
The eruption plume may have reached around 30 km into the atmosphere, making it enormous even by global standards.
What Is Tephra?
Tephra is volcanic material thrown into the air during an eruption.
It can include:
Fine ash
Small volcanic fragments
Pumice
Larger blocks
For scientists like Helga, tephra is a record of what happened during an eruption. By digging into layers of volcanic deposits, researchers can reconstruct the sequence of events.
In the case of Öræfajökull, tephra layers help reveal how the 1362 eruption unfolded, what materials were produced, and how the eruption affected the surrounding landscape.
The Threat of Pyroclastic Density Currents
One of the most serious hazards discussed in the episode is the pyroclastic density current, often shortened to PDC.
A PDC happens when an eruption column collapses and sends a fast-moving, extremely hot cloud of gas, ash, and volcanic material racing down the side of a volcano.
Helga describes it as something that erases everything in its path.
This matters because scientists now believe that, in the 1362 eruption, pyroclastic density currents may have been among the first major hazards—not just the glacial floods.
That changes how we think about evacuation and future volcanic risk.
Glacial Outburst Floods: When Ice Meets Fire
Because Öræfajökull is covered by ice, eruptions can also trigger jökulhlaups, or glacial outburst floods.
These floods occur when volcanic heat melts glacier ice, releasing large volumes of water that rush down from the mountain.
In Iceland, this is a familiar volcanic hazard because many of the country’s largest volcanoes sit beneath glaciers.
At Öræfajökull, that combination of volcano and glacier adds another layer of danger. A future eruption could involve both explosive volcanic activity and powerful floods.
The 1727 Eruption
Öræfajökull erupted again in 1727, but this eruption was different from the 1362 event.
It was smaller and occurred more on the flank of the volcano. It still caused glacial flooding, but it did not match the scale or explosiveness of the 1362 eruption.
For Helga, comparing the two eruptions is important because each one reveals something different about the volcano’s behavior.
How Do Scientists Study Öræfajökull Today?
Helga’s research goes deep—literally.
She studies experimental petrology, which means recreating volcanic conditions in the lab. Using tiny gold capsules, she melts volcanic material under controlled pressure, temperature, water, and carbon dioxide conditions.
In simple terms, she is creating miniature versions of possible Öræfajökull magmas.
This helps her understand:
What is happening beneath the volcano
How deep magma may be stored
What kinds of eruptions are possible
How different gases affect magma behavior
Which eruption scenarios are more likely
It is detailed, technical work, but the goal is practical: to better understand what Öræfajökull might do in the future.
Why Is Öræfajökull Hard to Monitor?
Monitoring Öræfajökull is challenging for several reasons.
The volcano is steep
It is covered by glacier ice
It sits away from Iceland’s main rift zone
Seismic instruments are harder to place
Satellite measurements are more complicated on steep, icy terrain
On flatter ground, scientists can more easily detect land rising as magma moves beneath the surface. But at Öræfajökull, the glacier and mountain shape make those signals harder to read.
That makes research like Helga’s especially important.
Is Öræfajökull Waking Up?
In 2016–2017, scientists observed unusual activity at Öræfajökull. A cauldron formed in the glacier surface, likely caused by heat from below.
That did not lead to an eruption, but it showed that something was happening beneath the ice.
Helga is careful not to overstate the risk. A future eruption could still be decades away—or longer. But the volcano has shown signs of stirring, and understanding those signs matters.
Could It Erupt Again?
Yes.
But that does not mean an eruption is imminent.
Öræfajökull has erupted before, and it will erupt again at some point. The key question is when, how, and what type of eruption it might produce.
A future eruption could be smaller, like 1727.
Or it could be more explosive, like 1362.
That uncertainty is exactly why scientists study past eruptions, magma chemistry, tephra deposits, and warning signs.
Why This Matters Today
A large explosive eruption at Öræfajökull today would not only affect the local area.
It could impact:
Roads and infrastructure in southeast Iceland
Nearby communities and farms
Tourism around Vatnajökull and the Ring Road
Air travel
Air quality
Emergency planning
The 2010 Eyjafjallajökull eruption disrupted air travel across Europe with a much smaller plume. Öræfajökull has the potential to produce something far larger.
Understanding the volcano is not about fear. It is about preparation.
A Final Thought: Respecting a Silent Volcano
Öræfajökull is one of Iceland’s most beautiful mountains. It is also one of its most powerful volcanoes.
For Helga, studying it brings both scientific fascination and deep respect. Standing before the glacier-covered peak, it is hard not to feel the contrast: peaceful on the surface, complex and powerful beneath.
That is what makes this episode so compelling.
It is a story about hidden danger, lost history, cutting-edge science, and the people working to understand Iceland’s volcanic future.
Listen to the Full Episode about Öræfajökull
Want to hear the full conversation?
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Learn more about terms in geology and volcanology
The Ultimate Guide to Icelandic Volcanoes: What Every Volcano Lover Should Know
Lava Academy Glossary: Terms in Geology and Volcanology, Part Two
