Eldgjá

Fire Chasm - Largest Lava Flood in History

934-940 AD Eruption Period
19.6 km³ Lava Volume
75 km Fissure Length

About Eldgjá (Fire Chasm)

Eldgjá, meaning "Fire Chasm" in Icelandic, is a massive volcanic fissure that produced the largest lava flood in recorded human history during its eruption in 934-940 AD, fundamentally shaping Iceland's landscape.

🌋 Volcanic System

  • Part of the Katla volcanic system
  • 75 km long fissure system
  • Located in southern Iceland highlands
  • Connected to Mýrdalsjökull glacier

📊 Eruption Scale

  • Lava volume: 19.6 km³
  • Area covered: 780 km²
  • Duration: 6 years (934-940 AD)
  • VEI: 4-5 (explosive phases)

🏔️ Geography

  • Elevation: 600-800m above sea level
  • Deepest point: 270m below rim
  • Width: up to 600m in places
  • Contains several lakes

Eldgjá Location & Fissure System

The massive Eldgjá fissure extends 75 kilometers across Iceland's southern highlands, creating one of the most spectacular volcanic chasms on Earth.

Map Legend

Eldgjá Fissure System (75km)
Mýrdalsjökull Glacier
Kirkjubæjarklaustur (nearest town)

Note: Access requires 4WD vehicle. Road conditions vary greatly depending on weather.

The Great Eruption of 934-940 AD

The Eldgjá eruption began around 934 AD and continued for approximately six years, producing the largest effusive eruption in recorded history and significantly impacting medieval Iceland.

Eruption Phases

934 AD

Eruption Begins

Initial explosive activity opens the fissure system. Ash and volcanic bombs are ejected from multiple vents.

934-936 AD

Massive Lava Effusion

Enormous volumes of lava flow from the fissure, creating the largest lava field in recorded history.

938-940 AD

Final Phases

Activity continues with intermittent explosive and effusive episodes before gradually declining.

940 AD

Eruption Ends

After six years, the eruption ceases, leaving behind a transformed highland landscape.

📜 Historical Evidence

The Eldgjá eruption is documented in medieval Icelandic sagas and chronicles. Ice core data from Greenland confirms the massive sulfur dioxide emissions, and the eruption may have contributed to climate cooling across the Northern Hemisphere during the 10th century.

Environmental Impact

🌍 Global Effects

  • Climate cooling in Northern Hemisphere
  • Sulfur emissions detected in ice cores
  • Possible crop failures in Europe
  • Atmospheric haze documented

🇮🇸 Local Impact

  • Massive landscape transformation
  • Rivers diverted by lava flows
  • Highland grazing areas destroyed
  • Settlement patterns changed

Geological Features

Eldgjá represents one of the most spectacular examples of fissure eruption geology, showcasing various volcanic processes and creating a unique highland landscape.

🪨 Rock Types

  • Basaltic lava: Tholeiitic composition
  • Scoria cones: Along fissure length
  • Tephra layers: Explosive deposits
  • Pillow lavas: Where lava met water

🏔️ Volcanic Features

  • Deep volcanic chasm (up to 270m)
  • Multiple crater rows
  • Lava channels and tubes
  • Rootless cones (pseudocraters)

💧 Hydrological Features

  • Several crater lakes
  • Diverted river systems
  • Groundwater interactions
  • Seasonal waterfalls

🧊 Glacial Interactions

  • Connection to Katla system
  • Subglacial volcanic activity
  • Jökulhlaup (glacial flood) potential
  • Ice-lava interaction features

🔬 Scientific Significance

Eldgjá provides crucial insights into large-scale basaltic fissure eruptions and their environmental impacts. The eruption serves as an analog for understanding similar prehistoric eruptions and helps scientists assess the potential impacts of future large-scale volcanic events.

Visiting Eldgjá

⚠️ Highland Expedition

Eldgjá is located in Iceland's remote central highlands. Access requires careful planning, 4WD vehicles, and highland driving experience. Weather conditions can change rapidly.

🚗 Access Routes

  • F208: Main highland route
  • F235: Alternative access
  • 4WD vehicle essential
  • River crossings required

🗓️ Best Time to Visit

  • June-September: Roads accessible
  • July-August: Most stable weather
  • Late August: Stunning autumn colors
  • Highland roads closed winter months

🥾 Hiking Opportunities

  • Rim walk along the chasm
  • Descent into selected areas
  • Photography at multiple viewpoints
  • Multi-day highland trekking

🎯 Key Highlights

  • Dramatic volcanic chasm views
  • Crater lakes and waterfalls
  • Vast lava field landscapes
  • Connection to Katla system

🎒 Essential Preparation

Vehicle Requirements

  • 4WD with high clearance
  • Spare tires and tools
  • Emergency communication device
  • Full fuel tank + extra fuel

Safety Equipment

  • GPS navigation system
  • Emergency food and water
  • Weather-appropriate clothing
  • First aid kit

🎓 Educational Experience

Eldgjá offers an unparalleled opportunity to witness the scale and power of volcanic processes. The site provides insights into Iceland's geological history, the impacts of large-scale eruptions, and the dynamic relationship between volcanism and landscape formation.