Record #00080Nature archive
The magnitude Mw 9.5 Valdivia earthquake of 22 May 1960 is the largest instrumentally recorded earthquake listed by USGS. The 1952 Kamchatka event, Mw 9.0, is a documented predecessor in the record progression.
Current Record
9.5Mw
Current record value
Moment magnitude (Mw) quantifies earthquake size from seismic moment and allows comparison of the largest events. Values for historical earthquakes may be reconstructed from legacy instrumental observations and later research.
USGS lists the earthquake off Kamchatka on 4 November 1952 at Mw 9.0 and describes it as the first recorded magnitude-nine earthquake.
The 22 May 1960 Chilean event reached Mw 9.5, eclipsing the 1952 event. Later large earthquakes, including Alaska in 1964 (Mw 9.2) and Sumatra in 2004 (Mw 9.1), have not surpassed it.
9.5 Mw
USGS states that the 22 May 1960 Chile earthquake, magnitude 9.5, was the largest ever recorded by seismic instruments.
9.0 Mw
USGS identifies this as the first recorded magnitude-nine earthquake; the listed moment magnitude reflects later scientific analysis. Superseded by Chile's Mw 9.5 in 1960.
The record conclusion has sufficient verification support.
Verification explanation pending
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