Reviewed by USGSChile16y ago
M4.5 earthquake 97 km SW of San Antonio, Chile
Wednesday, August 4, 2010, 21:09:13 UTC · 34.232°S, 72.330°W
A magnitude 4.5 earthquake struck 97 km SW of San Antonio, Chile on Wednesday, August 4, 2010, 21:09:13 UTC, at a depth of 15.0 km (shallow). USGS received 3 “Did You Feel It?” reports, with a maximum reported intensity of III (weak). It is the strongest earthquake within 300 km since an M4.6 on August 2, 2010.
- Magnitude
- 4.5
- Light · mb
- Depth
- 15 km
- Shallow
- Felt reports
- 3
- Max intensity III
- 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
85 tons of TNT
That is about 1/178 of the Hiroshima bomb. A magnitude 5.0 releases about 6 times more energy.
Tectonic setting
70 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
15 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
Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.
| Place | Intensity | Reports | Distance |
|---|---|---|---|
| Rancagua, Libertador General Bernardo OʿHiggins, Chile | III · Weak | 1 | 147 km |
| Santiago, Metropolitana, Chile | III · Weak | 1 | 178 km |
| Curicó, Maule, Chile | I · Not felt | 1 | 130 km |
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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.5 on September 1, 2010. 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 664 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.82010 Maule, Chile EarthquakeFebruary 27, 2010 · 216 km S of this epicenter
- 8.2The 1906 Valparaiso, Chile EarthquakeAugust 17, 1906 · 221 km NE of this epicenter
- 8.025 km WSW of Valparaíso, ChileMarch 3, 1985 · 129 km N of this epicenter
- 7.826 km WNW of San Carlos, ChileJanuary 25, 1939 · 230 km S of this epicenter
- 7.819 km NNE of Hacienda La Calera, ChileJuly 9, 1971 · 209 km NE of this epicenter
- 7.730 km NNE of Constitución, ChileDecember 1, 1928 · 95 km S of this epicenter
- 7.7103 km NW of Constitución, ChileJanuary 30, 1914 · 107 km SW of this epicenter
- 7.47 km SSE of La Ligua, ChileMarch 28, 1965 · 217 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 43 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 35,721 recorded deaths. The most severe:
- 1939M8.3
Chillan
25 Jan 1939 · 225 km away · intensity X
30,000 deaths$920 million damagetsunami
- 1906M8.2
South Central
17 Aug 1906 · 140 km away · intensity XI
4,000 deaths$100 million damagetsunami
- 2010M8.8
Maule, Concepcion, Talcahuano
27 Feb 2010 · 216 km away · intensity IX
558 deaths$30 billion damagetsunami
- 1965M7.3
Central
28 Mar 1965 · 229 km away
400 deaths$125 million damage
- 1928M7.6
Talca, Chillan, Santiago, San Fernando
1 Dec 1928 · 91 km away · intensity IX
279 deathsSevere damage ($5–24M)tsunami
- 1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 135 km away · intensity VIII
180 deaths$1.5 billion damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.