M6.6 earthquake 152 km WNW of Tocopilla, Chile

Friday, October 22, 1920, 12:09:55 UTC · 21.602°S, 71.579°W

A magnitude 6.6 earthquake struck 152 km WNW of Tocopilla, Chile on Friday, October 22, 1920, 12:09:55 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M6.8 on December 23, 1916.

Magnitude: 6.6; Strong · mw
Depth: 15 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: —; No ShakeMap
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquake

In context

How big was it, and why here?

Energy released

116 kilotons of TNT

That is about 8 times the Hiroshima bomb. It released about 243 times the energy of a magnitude 5.0.

Tectonic setting

31 km

from the nearest mapped plate boundary, between the Nazca and Altiplano plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

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 has not published any M2.5+ earthquake within 100 km in the 30 days after this event.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 5 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 22 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2,385 recorded deaths. The most severe:

1877M8.3
Off North Coast
10 May 1877 · 112 km away · intensity XI
2,385 deaths$2 million damagetsunami
1878M7.9
Tarapaca
23 Jan 1878 · 227 km away · intensity VIII
Severe damage ($5–24M)tsunami
1871M7.3
Chile
5 Oct 1871 · 212 km away · intensity X
Severe damage ($5–24M)tsunami
1869M7.5
Iquique, Pica; Peru: Tacna
24 Aug 1869 · 263 km away · intensity VIII
Limited damage (under $1M)tsunami
1836M7.5
Cobija
3 Jul 1836 · 172 km away
tsunami
1911M7.3
Northern
15 Sep 1911 · 183 km away
tsunami

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

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