Volcano Eruption Energy Calculator
Calculate the energy released by volcanic eruptions.
Convert between Volcanic Explosivity Index (VEI), erupted volume, and equivalent TNT or nuclear bomb yield.
What Is the Volcanic Explosivity Index (VEI)? The VEI was proposed by Christopher Newhall and Stephen Self in 1982 (United States). It is a logarithmic scale (like the Richter scale) measuring the explosiveness of volcanic eruptions. VEI increases by 1 for each 10-fold increase in erupted volume. Scale: 0 (gentle lava flow) to 8 (supervolcano — civilization-scale event).
VEI Scale and Volume VEI 0: < 10,000 m³ (Hawaiian lava flows — happens constantly). VEI 1: 10,000–1 million m³ (Stromboli, Italy — near-continuous since ancient times). VEI 2: 1–10 million m³ (Mount Unzen, Japan, 1990). VEI 3: 10–100 million m³ (Soufrière Hills, Montserrat, 1995–ongoing). VEI 4: 0.1–1 km³ (Eyjafjallajökull, Iceland, 2010 — disrupted European air travel). VEI 5: 1–10 km³ (Mount St. Helens, USA, 1980 — 1.2 km³ of material ejected). VEI 6: 10–100 km³ (Pinatubo, Philippines, 1991 — largest 20th-century eruption). VEI 7: 100–1,000 km³ (Tambora, Indonesia, 1815 — caused “Year Without a Summer”). VEI 8: >1,000 km³ (Yellowstone supervolcano, last eruption ~640,000 years ago).
Energy Calculation Thermal energy per unit volume of magma erupted: approximately 1 GJ/m³ (depends on magma type). Basaltic lava: ~1–2 GJ/m³. Rhyolitic eruptions: ~1.5 GJ/m³. Total energy released includes thermal energy, kinetic energy of ejecta, and seismic energy. A rough estimate: E ≈ 10¹³ J × 10^VEI (in joules, order of magnitude).
Comparison Scales 1 kiloton TNT = 4.184 × 10¹² J. 1 megaton TNT = 4.184 × 10¹⁵ J. “Little Boy” (Hiroshima bomb, 1945): ~15 kilotons TNT. Tsar Bomba (largest H-bomb, USSR, 1961): 50 megatons TNT. Pinatubo 1991: ~200 megatons TNT equivalent (thermal energy). Tambora 1815: ~800 megatons (thermal) — but much energy was magmatic heat, not explosion. Krakatoa 1883 (VEI 6): ~200 megatons. Heard 4,800 km away in Australia.
Famous Eruptions Tambora (Indonesia, 1815): VEI 7. 160 km³ ejected. ~71,000 killed. Global cooling 0.5°C. Krakatoa (Indonesia, 1883): VEI 6. 25 km³. Tsunami 30 m high. Heard around the world. Pinatubo (Philippines, 1991): VEI 6. 10 km³. Lowered global temp 0.5°C for 1–2 years. Mount St. Helens (USA, 1980): VEI 5. Lateral blast at 900 km/h. 57 killed. Eyjafjallajökull (Iceland, 2010): VEI 4. Disrupted air travel for weeks across Europe.