Apr 8, 2025
Askja: Iceland’s Remote Giant and the Birthplace of a Crater Lake
Tucked deep within the stark highlands of Iceland’s Vatnajökull National Park lies Askja, one of the country’s most remote and fascinating volcanic systems. Surrounded by lava deserts and wrapped in an almost lunar atmosphere, Askja is a destination steeped in volcanic history, dramatic landscapes, and ongoing geological intrigue. For geology enthusiasts with an appetite for exploration, Askja offers a rare look into the raw power of Iceland’s volcanic underworld.
A Volcanic Giant in Isolation
Askja’s isolation is part of its mystique. Located in Iceland’s highlands, far from settlements or paved roads, the volcano is only accessible during the summer months, when melting snow and milder weather conditions allow adventurous travelers to make the journey. Even then, getting there requires a rugged vehicle and a willingness to cross some of the country’s most barren terrain.
This isolation, however, is precisely what makes Askja all the more compelling. The surrounding Ódáðahraun lava field, a vast stretch of jagged basalt, is often described as otherworldly. In fact, it was this resemblance to extraterrestrial terrain that led NASA to train Apollo astronauts there in the 1960s, preparing them for the surface of the Moon.
A Landscape Created from Catastrophe
Askja is part of the Dyngjufjöll volcanic network and classified as a stratovolcano, a type of volcano known for both explosive and effusive eruptions. But what truly defines Askja today is its enormous caldera, created during one of the most violent eruptions in Iceland’s modern history.
In 1875, Askja erupted with devastating force. The explosion blew the top off the volcano, ejecting a massive cloud of ash and tephra that spread across the country and reached as far as Scandinavia. It was more than just a geological event, it was a national crisis. Ashfall poisoned water supplies, killed farm animals, and ruined crops, leading to widespread famine and a wave of emigration from Iceland to North America. The eruption was so intense that it changed the landscape forever.
The aftermath of that eruption created one of Iceland’s most iconic geological features: Öskjuvatn. This deep, cold caldera lake sits at the heart of Askja’s collapsed summit. Beside it lies Víti, a smaller crater created during the same eruption, now filled with milky-blue, geothermally heated water. Its name—Víti—translates to “Hell,” a nod to its eerie appearance and sulfurous scent.
The Prehistoric Power of Askja
Askja’s volcanic activity stretches back thousands of years. Around 10,000 years ago, lava flows from the volcano helped shape the massive Ódáðahraun lava desert. Later eruptions, approximately 2,500 years ago, deposited thick tephra layers that are still visible in Iceland’s soil record today.
These ancient eruptions weren’t isolated events; they were part of an ongoing tectonic drama along the boundary between the North American and Eurasian plates. As these plates pull apart, magma rises to the surface, feeding Iceland’s relentless volcanic systems, and Askja is one of the key players in that story.
Eruptions in the Modern Era
After the landmark 1875 event, Askja didn’t go quiet. A series of smaller eruptions between 1921 and 1929 produced lava flows near the caldera, adding fresh material to the already dramatic terrain. Then in 1961, the volcano erupted again, this time effusively, releasing basaltic lava south of the caldera. This marked Askja’s last eruption to date, but not necessarily its last chapter. In fact, signs suggest the volcano is waking up.
Is Askja Preparing to Erupt Again?
Since 2021, scientists in Iceland have observed clear signs of unrest beneath Askja. Satellite and GPS data show that the ground around the caldera has been steadily rising by more than 50 centimeters in some areas. This kind of uplift is a strong indication that magma is accumulating underground, increasing pressure within the volcano’s magma chamber.
In addition to ground inflation, temperatures in Öskjuvatn appear to be rising, possibly due to increased geothermal heat associated with magmatic activity. At the same time, seismic sensors have detected a growing number of small earthquakes, another telltale sign that something is shifting beneath the surface.
While it’s impossible to predict exactly when or how Askja might erupt, the data is clear: the system is active, and pressure is building.
What Makes Askja Special?
Askja’s uniqueness isn’t just in its geology, it’s in the way that geology is displayed so openly. Few volcanoes offer such a complete view of how explosive activity reshapes the landscape. From the vast, high-altitude lava fields to the water-filled caldera and steamy geothermal crater, Askja is a showcase of volcanic evolution.
Öskjuvatn is especially remarkable. Spanning approximately 11 square kilometers, this crater lake presents a stunning contrast to the surrounding black lava fields. Meanwhile, Víti invites brave visitors to soak in its warm, sulfurous waters, though conditions vary and safety should always be a priority.
How Scientists Monitor Askja
Given Askja’s explosive past and its growing signs of activity, Iceland’s scientists keep a close eye on the volcano using a network of modern monitoring tools. Seismometers detect earthquakes in the region, while GPS stations track changes in land elevation. Satellites provide thermal imagery, detect heat signatures, and measure surface deformation.
Together, these tools offer a layered understanding of what’s happening beneath the surface. When magma starts moving or pressure begins to rise, these instruments provide early warning signs that help officials prepare for potential eruptions. Iceland’s volcanic monitoring system is among the best in the world, and Askja is one of the volcanoes most closely watched.
A Geological Sibling to Giants
Askja is often compared to some of the world’s most famous volcanoes. Its 1875 eruption, for example, rivals Indonesia’s Krakatoa in terms of ash dispersal and global impact. The explosive potential and tephra fallout echo the behavior of Mount Vesuvius. Yet Askja stands apart because of its remote location, far from settlements, but still capable of affecting areas far beyond Iceland’s shores.
Its remoteness is both a blessing and a challenge. There are no towns nearby, and access is limited to short summer windows. But for those who make the journey, Askja delivers an unmatched experience of geological power and beauty.
Visiting Askja: What to Know
Traveling to Askja isn’t simple, but for those interested in Icelandic geology, it’s worth the effort. Reaching the caldera typically involves a multi-hour drive across rugged terrain, often in a 4-wheel drive vehicle. Weather conditions can change quickly, and parts of the route may require river crossings. Guided tours are recommended.
Askja is a living, shifting monument to the forces that have shaped and continue to shape Iceland. It’s a powerful reminder that the Earth is always changing, sometimes quietly, sometimes explosively, but always in motion.
