1960 Valdivia Earthquake: Magnitude 9.5 — Largest Ever Recorded

The 1960 Valdivia earthquake (Great Chilean Earthquake) struck on May 22, 1960, at 15:11 UTC, with a moment magnitude (Mw) of 9.5 — the largest earthquake ever instrumentally recorded.

Key Facts

• Epicenter: Near Lumaco, ~570 km south of Santiago, Chile.
• Depth: 33 km (shallow).
• Rupture length: ~1,000 km (Nazca Plate subducting under South American Plate).
• Duration: ~10 minutes of shaking.

Impacts

• Deaths: 1,000–6,000 (estimates vary; tsunami caused most far-field deaths).
• Homeless: 2 million.
• Tsunami: Waves up to 25 m (82 ft) in Chile; crossed Pacific — 61 dead in Hawaii, 138 in Japan, 32 in Philippines.
• Volcanic eruption: Cordón Caulle erupted 2 days later (triggered by quake).
• Economic loss: $400–800M (1960 USD) — ~$4–8B today.

Scientific Legacy

• Confirmed plate tectonics / subduction zone mechanics.
• Spurred Pacific Tsunami Warning System (1965).
• Benchmark for moment magnitude scale (Mw) development.

Comparison

Valdivia remains the gold standard for megaquake magnitude — a planetary reminder of subduction zone power.