M7.6 earthquake 77 km WSW of Callao, Peru

Thursday, October 3, 1974, 14:21:29 UTC · 12.265°S, 77.795°W

A magnitude 7.6 earthquake struck 77 km WSW of Callao, Peru on Thursday, October 3, 1974, 14:21:29 UTC, at a depth of 13.0 km (shallow). It is the strongest earthquake within 300 km since an M8.1 on October 17, 1966.

Magnitude: 7.6; Major · ms
Depth: 13 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VII; Very strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

3.8 megatons of TNT

That is about 252 times the Hiroshima bomb. It released about 7,943 times the energy of a magnitude 5.0.

Tectonic setting

102 km

from the nearest mapped plate boundary, between the Nazca and South American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: shallow

13 km

Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.

Did You Feel It?

Where it was felt

No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.

After the main event

Aftershocks within 200 km

USGS lists 27 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.3 on October 10, 1974. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 46 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 33 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 6,377 recorded deaths. The most severe:

1746M8.0
Lima, Callao
29 Oct 1746 · 71 km away · intensity XI
5,941 deathsExtreme damage ($25M+)tsunami
1940M8.2
Peru
24 May 1940 · 215 km away · intensity X
179 deathsSevere damage ($5–24M)tsunami
1966M8.1
Lima,Huacho,Huaura, Chancay,Supe,San Nicolas
17 Oct 1966 · 192 km away · intensity IX
110 deaths$35 million damagetsunami
1974M8.1
Lima, Callao
3 Oct 1974 · 1 km away · intensity IX
78 deaths$10 million damagetsunami
1828M8.3
Lima, Callao
30 Mar 1828 · 15 km away · intensity VII
30 deathsModerate damage ($1–5M)tsunami
1937M6.5
Huancabamba,Oxapampa,El Progreso,San David
24 Dec 1937 · 225 km away · intensity X
15 deathsModerate damage ($1–5M)

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers