Reviewed by USGSChile88y ago
M7.4 earthquake in Atacama, Chile
Tuesday, April 18, 1939, 06:22:44 UTC · 27.218°S, 70.875°W
A magnitude 7.4 earthquake struck in Atacama, Chile on Tuesday, April 18, 1939, 06:22:44 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.5 on July 13, 1936.
- Magnitude
- 7.4
- Major · mw
- Depth
- 35 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 earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
2.0 megatons of TNT
That is about 135 times the Hiroshima bomb. It released about 4,266 times the energy of a magnitude 5.0.
Tectonic setting
95 km
from the nearest mapped plate boundary, between the Nazca and South American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
35 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 has not published any M2.5+ earthquake within 200 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 30 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.594 km ENE of Vallenar, ChileNovember 11, 1922 · 156 km SE of this epicenter
- 8.060 km W of Diego de Almagro, ChileDecember 4, 1918 · 87 km N of this epicenter
- 7.583 km NNE of Taltal, ChileJuly 13, 1936 · 287 km N of this epicenter
- 7.550 km WNW of Diego de Almagro, ChileJune 8, 1909 · 124 km N of this epicenter
- 7.032 km NW of Fiambalá, ArgentinaAugust 3, 1920 · 298 km E of this epicenter
- 7.086 km NW of La Serena, ChileMarch 19, 1904 · 243 km S of this epicenter
- 7.0118 km WNW of Vallenar, ChileNovember 7, 1922 · 166 km SW of this epicenter
- 6.9103 km NNW of Coquimbo, ChileMay 20, 1918 · 241 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 21 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 721 recorded deaths. The most severe:
- 1922M8.5
Atacama
11 Nov 1922 · 156 km away · intensity XI
700 deathsSevere damage ($5–24M)tsunami
- 1899
La Rioja
12 Apr 1899 · 291 km away · intensity VIII
11 deathsModerate damage ($1–5M)
- 1859M7.6
Chile
5 Oct 1859 · 54 km away · intensity X
10 deathsUnder $1 million damagetsunami
- 1819M8.5
Copiapo
12 Apr 1819 · 66 km away · intensity X
Severe damage ($5–24M)tsunami
- 1819M8.0
Copiapo
4 Apr 1819 · 60 km away
Severe damage ($5–24M)
- 1918M7.8
Copiapo
4 Dec 1918 · 136 km away
Severe damage ($5–24M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.