M6.6 earthquake 16 km S of Comas, Peru

Wednesday, October 1, 1969, 05:05:48 UTC · 11.870°S, 75.094°W

A magnitude 6.6 earthquake struck 16 km S of Comas, Peru on Wednesday, October 1, 1969, 05:05:48 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on November 1, 1947.

Magnitude: 6.6; Strong · mw
Depth: 15 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: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

120 kilotons of TNT

That is about 8 times the Hiroshima bomb. It released about 251 times the energy of a magnitude 5.0.

Tectonic setting

197 km

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

Depth: shallow

15 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 100 km

USGS lists 9 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M6.0 on October 1, 1969. 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 26 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 32 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 6,580 recorded deaths. The most severe:

1746M8.0
Lima, Callao
29 Oct 1746 · 229 km away · intensity XI
5,941 deathsExtreme damage ($25M+)tsunami
1947M7.6
Satipo,Andamarca,Acobamba,La Merced,Victoc
1 Nov 1947 · 111 km away · intensity X
233 deathsSevere damage ($5–24M)
1940M8.2
Peru
24 May 1940 · 258 km away · intensity X
179 deathsSevere damage ($5–24M)tsunami
1969M6.6
Huaytapallana, Lampa, Chilifruta
1 Oct 1969 · 6 km away · intensity XI
130 deaths$5 million damage
1813
Ica
30 Mar 1813 · 250 km away · intensity VII
32 deathsModerate damage ($1–5M)
1828M8.3
Lima, Callao
30 Mar 1828 · 297 km away · intensity VII
30 deathsModerate damage ($1–5M)tsunami

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

Nearby trackers