Reviewed by USGSCosta Rica86y ago
M7.5 earthquake 70 km WSW of Golfito, Costa Rica
Friday, December 5, 1941, 20:47:03 UTC · 8.329°N, 83.694°W
A magnitude 7.5 earthquake struck 70 km WSW of Golfito, Costa Rica on Friday, December 5, 1941, 20:47:03 UTC, at a depth of 20.0 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on December 21, 1939.
- Magnitude
- 7.5
- Major · mw
- Depth
- 20 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
2.4 megatons of TNT
That is about 161 times the Hiroshima bomb. It released about 5,070 times the energy of a magnitude 5.0.
Tectonic setting
22 km
from the nearest mapped plate boundary, between the Cocos and Panama plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
20 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 1 M2.5+ earthquake within 200 km in the following 30 days; the largest was M6.9 on December 6, 1941. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 56 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.64 km WNW of Atenas, Costa RicaDecember 21, 1939 · 201 km NW of this epicenter
- 7.544 km ESE of Burica, PanamaJuly 18, 1934 · 140 km E of this epicenter
- 7.353 km SSE of Quepos, Costa RicaDecember 20, 1904 · 80 km NW of this epicenter
- 7.245 km SW of Quebrada de Piedra, PanamaJanuary 20, 1904 · 197 km E of this epicenter
- 7.16 km WNW of Siquirres, Costa RicaApril 24, 1916 · 199 km N of this epicenter
- 6.8south of PanamaJuly 18, 1934 · 174 km SE of this epicenter
- 6.813 km W of Jacó, Costa RicaDecember 22, 1939 · 184 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 20 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 706 recorded deaths. The most severe:
- 1910M6.4
Cartago, San Jose
4 May 1910 · 189 km away
700 deathsSevere damage ($5–24M)
- 1941M7.6
Costa Rica-Panama
5 Dec 1941 · 68 km away · intensity IV
6 deathsModerate damage ($1–5M)tsunami
- 1854M7.3
Costa Rica-Panama
5 Aug 1854 · 79 km away
Severe damage ($5–24M)tsunami
- 1888
San Jose, Ala Juela, Heredia
30 Dec 1888 · 186 km away · intensity VIII
Severe damage ($5–24M)
- 1822M7.6
Matina
7 May 1822 · 151 km away · intensity VII
Moderate damage ($1–5M)tsunami
- 1882M5.8
Alajuela, San Jose, Heredia
3 Mar 1882 · 111 km away · intensity VIII
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.