M7.9 earthquake 34 km SW of Chimbote, Peru

Sunday, May 31, 1970, 20:23:30 UTC · 9.266°S, 78.847°W

A magnitude 7.9 earthquake struck 34 km SW of Chimbote, Peru on Sunday, May 31, 1970, 20:23:30 UTC, at a depth of 58.4 km (shallow). It is the strongest earthquake within 300 km since an M8.1 on October 17, 1966.

Magnitude: 7.9; Major · mw
Depth: 58 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VIII; Severe (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

11 megatons of TNT

That is about 709 times the Hiroshima bomb. It released about 22,387 times the energy of a magnitude 5.0.

Tectonic setting

181 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

58 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 14 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.4 on June 4, 1970. 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 25 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 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 69,403 recorded deaths. The most severe:

1970M7.9
Northern, Pisco, Chiclayo
31 May 1970 · 9 km away · intensity X
66,794 deaths$530 million damagetsunami
1725M7.7
Trujillo, Ancash, Lima
7 Jan 1725 · 34 km away · intensity IX
1,500 deathsSevere damage ($5–24M)
1946M7.3
Jocaibamba,Cerro Angaschaj,Cerro Sillapata
10 Nov 1946 · 171 km away · intensity XI
800 deathsSevere damage ($5–24M)
1940M8.2
Peru
24 May 1940 · 244 km away · intensity X
179 deathsSevere damage ($5–24M)tsunami
1966M8.1
Lima,Huacho,Huaura, Chancay,Supe,San Nicolas
17 Oct 1966 · 166 km away · intensity IX
110 deaths$35 million damagetsunami
1937M6.5
Huancabamba,Oxapampa,El Progreso,San David
24 Dec 1937 · 293 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