M4.8 earthquake 29 km NE of Constitución, Chile

Saturday, October 16, 2010, 12:03:07 UTC · 35.124°S, 72.203°W

A magnitude 4.8 earthquake struck 29 km NE of Constitución, Chile on Saturday, October 16, 2010, 12:03:07 UTC, at a depth of 31.5 km (shallow). USGS received 6 “Did You Feel It?” reports, with a maximum reported intensity of III (weak). It is the strongest earthquake within 300 km since an M4.8 on October 12, 2010.

Magnitude: 4.8; Light · mb
Depth: 32 km; Shallow
Felt reports: 6; 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

239 tons of TNT

That is about 1/63 of the Hiroshima bomb. A magnitude 5.0 releases about 2 times more energy.

Tectonic setting

129 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

32 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
Talca, Maule, Chile	III · Weak	3	67 km
Santiago, Metropolitana, Chile	II · Weak	2	236 km
Viña del Mar, Valparaíso, Chile	III · Weak	1	244 km

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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.1 on November 11, 2010. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

4.148 km W of Rauco, Chile16y ago · 42 km NE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 651 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 39 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 35,238 recorded deaths. The most severe:

1939M8.3
Chillan
25 Jan 1939 · 125 km away · intensity X
30,000 deaths$920 million damagetsunami
1906M8.2
South Central
17 Aug 1906 · 237 km away · intensity XI
4,000 deaths$100 million damagetsunami
2010M8.8
Maule, Concepcion, Talcahuano
27 Feb 2010 · 128 km away · intensity IX
558 deaths$30 billion damagetsunami
1928M7.6
Talca, Chillan, Santiago, San Fernando
1 Dec 1928 · 23 km away · intensity IX
279 deathsSevere damage ($5–24M)tsunami
1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 226 km away · intensity VIII
180 deaths$1.5 billion damagetsunami
1822M8.5
Valparaiso, Quillota, Concon, Aconcagua
20 Nov 1822 · 237 km away · intensity XI
72 deathsExtreme damage ($25M+)tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers