The Biggest Earthquakes Ever Recorded by Magnitude

The Strongest Earthquakes Ever Recorded

Five megathrust events dominate the instrumental record. Each occurred along a subduction zone, where one tectonic plate descends beneath another and stores strain over centuries before releasing it. The five events ranked by magnitude are:

• 1960 Valdivia earthquake, Chile
• 1964 Alaska earthquake, United States
• 2004 Indian Ocean earthquake
• 2011 Tōhoku earthquake, Japan
• 1952 Kamchatka earthquake, Russia

1960 Valdivia Earthquake, Chile: Magnitude 9.5

On 22 May 1960, a rupture off southern Chile reached Mw 9.5, the largest earthquake ever recorded by seismic instruments. The fault slipped along roughly 1,000 kilometres of the boundary between the Nazca and South American plates. A Pacific-wide tsunami followed, reaching Hawaii, Japan and the Philippines within a day, and the nearby Cordón Caulle volcano erupted days later.

1964 Alaska Earthquake, United States: Magnitude 9.2

The Good Friday event of 27 March 1964 struck Prince William Sound at Mw 9.2. Rupture occurred along the Alaska-Aleutian megathrust, lifting and dropping long stretches of coastline. Local tsunamis caused damage along the Gulf of Alaska. Alaska's shock is not the strongest earthquake ever measured. Still, it reshaped seismology, since studies of the ground deformation supported the emerging theory of plate tectonics.

2004 Indian Ocean Earthquake: Magnitude 9.1

On 26 December 2004, the Sumatra-Andaman rupture reached Mw 9.1 along about 1,300 kilometres of fault beneath the eastern Indian Ocean. Seismic stations around the world captured the event in full. It remains the biggest earthquake measured in that region, and the resulting tsunami prompted the creation of a regional warning system.

2011 Tōhoku Earthquake, Japan: Magnitude 9.0

A Mw 9.0 megathrust event struck the Japan Trench on 11 March 2011, where the Pacific plate dives beneath Honshu. The earthquake epicenter lay about 130 kilometres offshore. Waves overtopped coastal defences and triggered the Fukushima Daiichi nuclear accident. Tōhoku sits below the largest earthquake ever measured in Chile, yet no other great earthquake has been recorded by so many instruments.

1952 Kamchatka Earthquake, Russia: Magnitude 9.0

A Mw 9.0 rupture struck off the Kamchatka Peninsula on 4 November 1952, following the Kuril-Kamchatka trench. The tsunami crossed the Pacific and reached Hawaii, where it caused damage without reported loss of life. The event rarely enters popular rankings of the biggest earthquake ever documented, though it belongs firmly among the top five.

Magnitude answers a narrow question: how much energy a fault released. Intensity, casualties and tsunami height follow separate patterns, so a smaller shock can prove far more destructive than the biggest earthquake in history. Dense seismic monitoring now captures great ruptures within minutes. Building codes, tsunami alerts and earthquake preparedness turn that data into practical protection for coastal communities.