Reviewed by USGSChile41y ago
M3.9 earthquake 90 km W of San Antonio, Chile
Wednesday, June 5, 1985, 01:15:26 UTC · 33.670°S, 72.580°W
A magnitude 3.9 earthquake struck 90 km W of San Antonio, Chile on Wednesday, June 5, 1985, 01:15:26 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 3.9
- Minor · mb
- Depth
- 33 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: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
11 tons of TNT
That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.
Tectonic setting
30 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
33 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 50 km
USGS lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.4 on June 18, 1985. 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 228 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 · 179 km NE of this epicenter
- 8.145 km NNW of Illapel, ChileApril 6, 1943 · 291 km NE of this epicenter
- 8.025 km WSW of Valparaíso, ChileMarch 3, 1985 · 89 km NE of this epicenter
- 7.826 km WNW of San Carlos, ChileJanuary 25, 1939 · 294 km S of this epicenter
- 7.819 km NNE of Hacienda La Calera, ChileJuly 9, 1971 · 176 km NE of this epicenter
- 7.730 km NNE of Constitución, ChileDecember 1, 1928 · 160 km S of this epicenter
- 7.7103 km NW of Constitución, ChileJanuary 30, 1914 · 139 km SW of this epicenter
- 7.47 km SSE of La Ligua, ChileMarch 28, 1965 · 181 km NE of this epicenter
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 35,032 recorded deaths. The most severe:
- 1939M8.3
Chillan
25 Jan 1939 · 288 km away · intensity X
30,000 deaths$920 million damagetsunami
- 1906M8.2
South Central
17 Aug 1906 · 92 km away · intensity XI
4,000 deaths$100 million damagetsunami
- 1965M7.3
Central
28 Mar 1965 · 191 km away
400 deaths$125 million damage
- 1928M7.6
Talca, Chillan, Santiago, San Fernando
1 Dec 1928 · 157 km away · intensity IX
279 deathsSevere damage ($5–24M)tsunami
- 1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 101 km away · intensity VIII
180 deaths$1.5 billion damagetsunami
- 1971M7.8
Central
9 Jul 1971 · 183 km away · intensity IX
83 deaths$236 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.