Katla

The Hidden Giant Under Ice

1918 Last Major Eruption
750m Ice Thickness Above
300,000 m³/s Flood Volume

About Katla

Katla lies beneath the Mýrdalsjökull ice cap in southern Iceland. The central caldera is ~10 km wide and is hidden beneath 590 km² of ice. The volcano rises to ~1,500 m above sea level. When Katla erupts, it causes catastrophic glacial floods that can match the flow of the Amazon River.

🌋 Volcanic Power

  • One of Iceland's largest volcanic systems
  • Caldera: ~10 km wide
  • Peak elevation: ~1,500 m above sea level
  • At least 21 eruptions in last 1,100 years
  • Average repose period: ~50 years
  • Currently overdue (107 years since major eruption)

🧊 Glacier Coverage

  • Buried under Mýrdalsjökull ice cap
  • Ice thickness: up to 750m
  • Glacier area: 590 km²
  • Black ash stripes in ice from eruptions

Eruption Danger

🌊 Jökulhlaup - Glacial Floods

When Katla erupts under the glacier, it melts massive amounts of ice instantly, creating floods with flow rates up to 300,000 m³/s - comparable to the Amazon River. These floods can destroy everything in their path within hours.

Historical Eruptions

  • 1918: VEI 5 event, 5-week eruption, massive floods extended coastline by 5 km due to lahar deposits. Flood discharges may have reached 300,000 m³/s
  • 1755: Major explosive eruption that caused flooding and extended Iceland's coastline
  • 1625: Major explosive eruption killed 100+ people
  • 934 CE: Eldgjá fissure eruption (part of Katla system) - largest lava flow in history

Warning Signs

  • Earthquake swarms under glacier
  • Glacial floods without eruption
  • Increased geothermal activity
  • GPS shows ground deformation

20th Century Minor Eruptions

Smaller subglacial eruptions occurred in 1955, 1999, and 2011. These eruptions did not break through the ice but caused jökulhlaups and intense seismicity.

🔥 The Eldgjá Connection

Part of Katla's volcanic system, the Eldgjá fissure eruption lasted from 934–940 CE and produced ~19.6 km³ of basaltic lava. It likely caused climate cooling and societal impacts across the Northern Hemisphere. This was the world's largest lava flood in recorded history.

24/7 Monitoring

Katla is one of the world's most closely monitored volcanoes due to its extreme danger.

📡 Monitoring Systems

  • 20+ seismometers around volcano
  • GPS stations track ground movement
  • River monitoring for flood detection
  • Gas emission measurements

🚨 Emergency Plans

  • Automated alert systems
  • Evacuation routes established
  • 30-minute evacuation window
  • Regular evacuation drills

Katla Ice Cave

A unique year-round ice cave featuring dramatic black ice formed from layers of volcanic ash.

Cave Features

  • Black and blue striped ice walls
  • Formed by geothermal heat from volcano
  • Accessible year-round (unlike glacier caves)
  • Dragon glass appearance from ash

Tour Information

  • Access: Super jeep required
  • Duration: 3-4 hour tours
  • Departure: From Vík
  • Season: Year-round access