Katla — The Sleeping Giant
A massive volcano buried beneath 750m of ice — and overdue for its next eruption
Katla lies beneath the Mýrdalsjökull ice cap in southern Iceland. Its central caldera is approximately 10 km wide, buried under up to 750 meters of ice spanning 590 km². When Katla erupts, it creates catastrophic glacial floods — jökulhlaups — that can match the flow of the Amazon River. Katla has not had a major eruption since 1918, making it significantly overdue.
Scale & Power
- One of Iceland's largest volcanic systems
- Caldera: approximately 10 km wide
- Buried under Mýrdalsjökull — 590 km² of ice
- Ice thickness above: up to 750 m
- At least 21 eruptions in the last 1,100 years
- Currently overdue — 107+ years since last major eruption
Jökulhlaup — Glacial Flood Danger
When Katla erupts under the glacier, it instantly melts enormous quantities of ice, creating floods with flow rates up to 300,000 m³/s — comparable to the Amazon River. These floods surge across the sandur plains within minutes, destroying everything in their path.
The 1918 eruption extended Iceland's south coast by 5 km as the jökulhlaup carried vast amounts of rock and sediment to the sea. Modern infrastructure, including the Ring Road, is now protected by raised embankments.
Historical Eruptions
- 934 CE: Eldgjá fissure eruption (Katla system) — largest lava flood in recorded history
- 1625: Major explosive eruption killed 100+ people
- 1755: Major eruption caused flooding and extended Iceland's coastline
- 1918: VEI 5 event lasting 5 weeks — floods extended south coast by 5 km
The Katla Ice Cave
A unique year-round ice cave in Mýrdalsjökull features dramatic black ice formed from layers of volcanic ash deposited by previous eruptions. The black and blue striped walls give the cave an otherworldly appearance.
Access requires a super jeep tour from Vík, taking approximately 3–4 hours. Unlike seasonal glacier ice caves, the Katla cave is accessible year-round due to geothermal heat from below.
Monitoring
Katla is one of the world's most closely monitored volcanoes due to its extreme danger potential.
- 20+ seismometers surrounding the volcano
- GPS stations track ground movement
- River sensors detect early flood signals
- Gas emission measurements
- Automated alert systems
- Vík has established evacuation routes and a 30-minute evacuation window
Safety Information
Katla can erupt with approximately 30 minutes warning. If you are in Vík and hear sirens, move immediately to high ground. Do not attempt to cross the sandur plains during or after a jökulhlaup warning.