Reviewed by USGSChile10y ago
M4.6 earthquake 27 km WSW of Illapel, Chile
Wednesday, March 23, 2016, 00:38:00 UTC · 31.769°S, 71.418°W
A magnitude 4.6 earthquake struck 27 km WSW of Illapel, Chile on Wednesday, March 23, 2016, 00:38:00 UTC, at a depth of 42.7 km (shallow). USGS received 1 “Did You Feel It?” report, with a maximum reported intensity of III (weak). It is the strongest earthquake within 300 km since an M4.7 on March 19, 2016.
- Magnitude
- 4.6
- Light · mwr
- Depth
- 43 km
- Shallow
- Felt reports
- 1
- 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
120 tons of TNT
That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.
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
43 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 |
|---|---|---|---|
| La Ligua, Valparaíso, Chile | III · Weak | 1 | 89 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 M5.3 on April 6, 2016. 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 920 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.348 km W of Illapel, ChileSeptember 16, 2015 · 33 km NW of this epicenter
- 8.2The 1906 Valparaiso, Chile EarthquakeAugust 17, 1906 · 70 km S of this epicenter
- 8.145 km NNW of Illapel, ChileApril 6, 1943 · 57 km N of this epicenter
- 8.025 km WSW of Valparaíso, ChileMarch 3, 1985 · 158 km S of this epicenter
- 7.819 km NNE of Hacienda La Calera, ChileJuly 9, 1971 · 97 km S of this epicenter
- 7.47 km SSE of La Ligua, ChileMarch 28, 1965 · 85 km S of this epicenter
- 7.419 km S of Valparaíso, ChileMarch 4, 1985 · 162 km S of this epicenter
- 7.237 km S of San Antonio, ChileMarch 18, 1931 · 240 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 58 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 29,206 recorded deaths. The most severe:
- 1861
Mendoza, San Luiz
20 Mar 1861 · 271 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
- 1944M6.9
San Juan Province
15 Jan 1944 · 279 km away · intensity IX
10,000 deaths$100 million damage
- 1906M8.2
South Central
17 Aug 1906 · 147 km away · intensity XI
4,000 deaths$100 million damagetsunami
- 1965M7.3
Central
28 Mar 1965 · 73 km away
400 deaths$125 million damage
- 1920M6.7
Mendoza
17 Dec 1920 · 284 km away · intensity VIII
400 deathsSevere damage ($5–24M)
- 1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 154 km away · intensity VIII
180 deaths$1.5 billion damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.