Reviewed by USGSChile56y ago
M5.2 earthquake 39 km SW of Illapel, Chile
Friday, July 9, 1971, 21:17:56 UTC · 31.912°S, 71.438°W
A magnitude 5.2 earthquake struck 39 km SW of Illapel, Chile on Friday, July 9, 1971, 21:17:56 UTC, at a depth of 50.1 km (shallow). It is the strongest earthquake within 300 km since an M5.5 on July 9, 1971.
- Magnitude
- 5.2
- Moderate · mw
- Depth
- 50 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 earthquakeDashed circle: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
951 tons of TNT
That is about 1/16 of the Hiroshima bomb. It released about 2 times the energy of a magnitude 5.0.
Tectonic setting
121 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
50 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 75 km
USGS lists 3 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M6.4 on July 11, 1971. 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 88 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.2The 1906 Valparaiso, Chile EarthquakeAugust 17, 1906 · 54 km S of this epicenter
- 8.145 km NNW of Illapel, ChileApril 6, 1943 · 73 km N of this epicenter
- 7.819 km NNE of Hacienda La Calera, ChileJuly 9, 1971 · 82 km S of this epicenter
- 7.47 km SSE of La Ligua, ChileMarch 28, 1965 · 71 km S of this epicenter
- 7.237 km S of San Antonio, ChileMarch 18, 1931 · 224 km S of this epicenter
- 7.086 km NW of La Serena, ChileMarch 19, 1904 · 296 km N of this epicenter
- 7.060 km WSW of Coquimbo, ChileApril 19, 1955 · 204 km N of this epicenter
- 6.94 km ESE of Chimbas, ArgentinaJanuary 15, 1944 · 283 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 38 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 28,989 recorded deaths. The most severe:
- 1861
Mendoza, San Luiz
20 Mar 1861 · 267 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
- 1944M6.9
San Juan Province
15 Jan 1944 · 283 km away · intensity IX
10,000 deaths$100 million damage
- 1906M8.2
South Central
17 Aug 1906 · 132 km away · intensity XI
4,000 deaths$100 million damagetsunami
- 1965M7.3
Central
28 Mar 1965 · 59 km away
400 deaths$125 million damage
- 1920M6.7
Mendoza
17 Dec 1920 · 286 km away · intensity VIII
400 deathsSevere damage ($5–24M)
- 1971M7.8
Central
9 Jul 1971 · 69 km away · intensity IX
83 deaths$236 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.