Reviewed by USGSChile41y ago
M5.1 earthquake 48 km NW of San Vicente, Chile
Wednesday, October 9, 1985, 13:42:52 UTC · 34.120°S, 71.449°W
A magnitude 5.1 earthquake struck 48 km NW of San Vicente, Chile on Wednesday, October 9, 1985, 13:42:52 UTC, at a depth of 54.1 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on September 27, 1985.
- Magnitude
- 5.1
- Moderate · mb
- Depth
- 54 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
674 tons of TNT
That is about 1/22 of the Hiroshima bomb. It released about 1 times the energy of a magnitude 5.0.
Tectonic setting
141 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
54 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 M4.5 on October 12, 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 254 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 · 191 km N of this epicenter
- 8.025 km WSW of Valparaíso, ChileMarch 3, 1985 · 116 km N of this epicenter
- 7.826 km WNW of San Carlos, ChileJanuary 25, 1939 · 252 km S of this epicenter
- 7.819 km NNE of Hacienda La Calera, ChileJuly 9, 1971 · 169 km N of this epicenter
- 7.730 km NNE of Constitución, ChileDecember 1, 1928 · 131 km SW of this epicenter
- 7.7103 km NW of Constitución, ChileJanuary 30, 1914 · 185 km SW of this epicenter
- 7.47 km SSE of La Ligua, ChileMarch 28, 1965 · 180 km N of this epicenter
- 7.419 km S of Valparaíso, ChileMarch 4, 1985 · 103 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 37 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 49,047 recorded deaths. The most severe:
- 1939M8.3
Chillan
25 Jan 1939 · 248 km away · intensity X
30,000 deaths$920 million damagetsunami
- 1861
Mendoza, San Luiz
20 Mar 1861 · 286 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
- 1906M8.2
South Central
17 Aug 1906 · 135 km away · intensity XI
4,000 deaths$100 million damagetsunami
- 1965M7.3
Central
28 Mar 1965 · 193 km away
400 deaths$125 million damage
- 1928M7.6
Talca, Chillan, Santiago, San Fernando
1 Dec 1928 · 110 km away · intensity IX
279 deathsSevere damage ($5–24M)tsunami
- 1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 112 km away · intensity VIII
180 deaths$1.5 billion damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.