Krafla Volcano: The (Lava) Fires of Krafla and Iceland’s Most Dynamic Volcanic System

Explore Krafla volcano in North Iceland, known for lava fissures of the Fires of Krafla, geothermal activity, and a few very hot boreholes.

In Iceland, the word eldar – or “fires” in English – has long been used to describe prolonged volcanic episodes involving repeated fissure eruptions, earthquakes, ground deformation, and magma movement. Rather than a single dramatic explosion, a “fire” is often a years-long volcanic event in which the Earth rips and rifts apart punctuated by ribbons of erupting lava. Famous examples include the devastating Laki Fires and the medieval (and modern, too) Reykjanes Fires.

Among the most scientifically important of these events are the Krafla Fires, a dramatic nine-year sequence of rifting events and eruptions in northeastern Iceland that transformed how volcanologists understand plate spreading and magma movement beneath Iceland.

Today, many scientists view Krafla as one of the best modern analogs for what is currently unfolding at Svartsengi on the Reykjanes Peninsula. The repeated magma intrusions, episodic fissure eruptions, inflation-deflation cycles, and crustal stretching now occurring near Grindavík strongly resemble the processes observed at Krafla nearly fifty years ago.

Wide view across the lava-covered shores of Lake Mývatn in North Iceland, with large volcanic craters and flat-topped tuya mountains rising in the distance beneath dramatic clouds and blue sky.

Large craters in the distance of the shores of Lake Mývatn. It is interesting to know that the Lake Mývatn caldera and these nearby tuya mountains are NOT apart of the Krafla volcanic system, and are part of a less active, overlapping system. Photo credit: Jessica Poteet

But Krafla is more than a story about volcanic eruptions. It is also one of the world’s most fascinating geothermal regions, where humans have drilled directly into magma itself. Wells at Krafla have accidentally erupted molten rock, and inspired revolutionary ideas about harvesting energy directly from Earth’s magma. Few places on Earth demonstrate the intersection of volcanism, tectonics, and geothermal power as dramatically as Krafla.

Quick Facts about Krafla

Recent Eruption Dates: 1975–1984 (Krafla Fires); 1724-1729 (Mývatn Fires)
Location: Northeastern Iceland, near Mývatn
Volcanic System: Krafla volcanic system, in the Northern Volcanic Zone (NVZ)
Eruption Type: Early in lifecycle: central shield volcano; now: fissure eruptions
Lava Area: ±35 km² during the Krafla Fires
Geothermal System Area: 40 km²
Total Volcanic System Area: 900-1100 km² (historical fissure zone is 90 km long)
Lava Type: Primarily basaltic lava, early central volcano eruptions had rhyolite mixtures
Gas Emissions: Notably small
Significance: A world-famous example of active continental rifting, magma intrusion, geothermal development, and magma-drilling research

Steaming geothermal landscape at the Hverir geothermal area near Krafla in North Iceland, featuring bubbling mud pools, fumaroles, mineral-stained earth, and volcanic mountains under a dramatic cloudy sky.

The Hverir geothermal area is an active geological area adjacent to the Krafla central volcano and south of the Krafla Fires lava fields. This area is a wonderful tourist area with nature paths and hiking trails. It is not usually busy and features amazing mud pools, boiling fumaroles, and bubbly hydrothermal features, with views of nearby Krafla volcanic system craters. Photo credit: Jessica Poteet

The Krafla Fires: Iceland Tearing Apart in Real Time

The Krafla volcanic system sits directly on the boundary between the North American and Eurasian tectonic plates, where the crust is slowly being pulled apart by the Mid-Atlantic Ridge. Unlike many volcanic systems that erupt in isolated events separated by centuries, Krafla behaves episodically. Long quiet periods are interrupted by intense rifting in which magma repeatedly intrudes into the crust over years or decades.

The Krafla Fires began dramatically in December 1975, when an unusual earthquake swarm struck the region. Scientists observed the ground rapidly deforming as magma accumulated beneath the caldera before suddenly draining sideways through underground fractures called dikes. This pattern would repeat itself again and again over the next nine years.

Overall, there were nine eruptions during this period, and 20 total distinct inflation-deflation magmatic events that warped the landscape. This behavior seen there is one of the clearest demonstrations ever recorded of how plate spreading actually occurs in Iceland (and maybe elsewhere in the world). Rather than spreading gradually and evenly, tectonic extension accumulates stress over time before being released in sudden pulses during rifting episodes. So, this Krafla-style rifting looks like:

Magma accumulates in the central volcano region of Krafla, under its caldera
Instead of erupting upward, it would reach a certain pressure, and suddenly push through existing rock laterally for Kilometers, forming dikes
The caldera region would deflate measurably (similar to Kiluaea pre-eruption)
The ground directly above the dikes would subside (sink down) and create a graben
The land adjacent and parallel to the dikes would rise up and create a horst
The dikes would erupt in elongated fissures kilometers away from the original subsurface magma collection area

Over time, through these periods of magma movement, ground deformation and faulting, and subsequent eruption, the earth rifts and widens.

Wide view of the geothermal fields at Námaskarð Pass near Lake Mývatn in Iceland, featuring steaming vents, orange and white mineral-stained earth, walking paths, and distant volcanic mountains beneath a dramatic blue sky.

The colorful geothermal landscape of Námaskarð Pass near Lake Mývatn in North Iceland, where steaming fumaroles, bubbling mud pools, and mineral-rich ground reveal the powerful geothermal activity beneath the Krafla volcanic system.

Using the Krafla Fires as a Parallel to the Reykjanes Fires

The parallels with modern activity at the Svartsengi volcanic system and the eruptions at Sundhnúkur are striking. On the Reykjanes Peninsula today, magma repeatedly accumulates beneath the crust before propagating laterally in dikes toward eruptive fissures. Inflation and deflation cycles, earthquake swarms, and episodic eruptions all mirror the patterns documented during the Krafla Fires. In both systems, magma appears to move in pulses rather than through continuous steady flow. Even the now-prolonged wait in between eruptions at Svartsengi was seen at Krafla; could we be waiting years for the next volcanic event at Sundhnúkur?

One of the most fascinating aspects of Krafla is how episodic its eruptive history appears to be, with hundreds to a thousand years between fissure swarms. Geological evidence suggests the system undergoes long dormant periods punctuated by concentrated episodes of tectonic and volcanic unrest. This behavior is characteristic of Icelandic rift zones, and is something we also see on Reykjanes and its 5-6 volcanic systems. Rather than erupting continuously, volcanic systems along spreading centers often store tectonic stress and magma pressure for decades or centuries before releasing that energy during intense “fire” episodes.

One major difference, however, is geography. Krafla is located in a sparsely populated region, while the Svartsengi system threatens infrastructure and communities such as Grindavík and the famous Blue Lagoon. Yet scientifically, Krafla offers an invaluable roadmap for understanding what prolonged rifting episodes on the Reykjanes Peninsula may look like over years, and even centuries. What knowledge will we gain at Svartsengi that will help us predict the next eruptive series at Krafla in a few hundred years?

View of the Krafla geothermal power station in Iceland, with steam rising from geothermal facilities surrounded by green volcanic hills, winding roads, and distant mountains under cloudy skies.

The Krafla geothermal power station in North Iceland, harnessing volcanic heat from the active Krafla volcanic system to generate renewable energy amid dramatic volcanic landscapes.

Touching Magma: What Happens When We Drill into Molten Rock?

Krafla is not only famous for eruptions. It is also one of the most extraordinary geothermal research sites in the world. The region hosts the Krafla Power Station, where high-temperature geothermal fluids are used to generate electricity. But drilling in such an active volcanic system comes with unusual risks. At Krafla, engineers have repeatedly encountered magma directly beneath the geothermal field.

One of the most remarkable incidents involved a borehole drilled in 1968, prior to the onset of the Krafla Fires. Years later, in 1977, two years after renewed magma movements associated with this volcanic rifting episode, magma intruded (moved in the subsurface) into the well. While the borehole itself was very far south of the active lava field at the time, it was directly along the dike propagation path between the central volcano and the active fissure area. The borehole reportedly expelled roughly three tons of molten material to the surface, effectively becoming a tiny artificial volcanic vent created by drilling.

Even more famous was the accidental magma encounter during the Iceland Deep Drilling Project (IDDP) in 2009. Engineers drilling deep beneath Krafla unexpectedly intersected rhyolitic magma at approximately 2.1 kilometers depth. Rather than destroying the project entirely, the well survived long enough for researchers to study superheated fluids reaching temperatures above 400°C.

The discovery was revolutionary. Scientists realized that geothermal wells drilled near magma could potentially produce enormous amounts of energy far beyond conventional geothermal systems. The heat available near magma bodies is immense, raising the possibility of “supercritical” geothermal power plants capable of dramatically increasing energy output.

At the same time, these events revealed the dangers of drilling into an active volcanic system. Wells can fail catastrophically, magma can intrude unexpectedly, and volcanic gases can create severe hazards. Krafla therefore sits at the frontier between energy innovation and volcanic risk.

Learn more about how Iceland harnesses geothermal energy in the Lava Academy Podcast Episode: Geothermal 101 which features and interview with geologist and science communicator Kári Valgeirsson

Krafla Volcano Q&A Section

Did Krafla erupt continuously from 1975 to 1984?

No. The Krafla Fires consisted of many separate rifting and eruptive events spread across nearly a decade. Some episodes caused only earthquakes and ground deformation, while others produced lava eruptions. This is very close to what we see on Reykjanes, too.

Is “Krafla” named after a Norse god?

Probably not. The name likely derives from an old Icelandic word related to cracking or fissuring, an appropriate description for a volcanic system where the ground repeatedly splits apart. Although, it is important to note that other “fire” events within the Krafla volcanic system have different names related to nearby, modern geographic places.

Is Krafla dangerous today?

Yes and no. It is closely monitored, and next to important geothermal power infrastructure. That said, while the volcanic system remains active, future eruptions or rifting episodes are not expected for a few more hundred years at a minimum and located within a rather sparsely populated area.

Could Iceland really use magma for energy?

Potentially. The IDDP project demonstrated that drilling near magma may allow access to extremely high-temperature geothermal fluids capable of producing far more energy than traditional geothermal wells. To learn more, read about the Krafla Magma Testbed project .

Aerial view of the Krafla lava fields at Leirhnjúkur in Iceland, featuring expansive black basalt lava flows, geothermal activity, volcanic craters, and rugged terrain beneath dramatic storm clouds.

Aerial drone view of the Leirhnjúkur lava fields within the Krafla volcanic system in North Iceland, showcasing vast black lava flows, geothermal pools, and volcanic terrain shaped during the Krafla Fires.

Conclusion

Krafla is one of the most important volcanic systems on Earth for understanding how Iceland geology and glocal plate rifting tectonics work. Here, scientists witnessed plate growth unfolding in real time, with modern tools, as magma repeatedly ripped through the crust during the Krafla Fires. The system revealed that Iceland’s rift zones can operate episodically, with centuries of quiet interrupted by dramatic pulses of volcanic and tectonic activity.

Today, the lessons learned at Krafla are helping scientists interpret the ongoing eruptions and dike intrusions at Svartsengi and future events across the Reykjanes Peninsula. The similarities between these events suggest Iceland may once again be entering a prolonged period of rifting and fissure volcanism.

At the same time, Krafla represents the cutting edge of geothermal science. From wells that accidentally erupted lava to drilling projects that intersected magma directly, the volcano has reshaped humanity’s understanding of Earth’s internal heat and the possibilities of geothermal energy.

Few places better capture Iceland’s identity as a land being actively created and power being actively generated, as the Krafla volcanic system. If you want to be immersed in the science behind this fissure system, as well as other fissure systems in Iceland, and compare them large central volcano systems, the Lava Show is the first place you should go to ask questions and learn more.