M4.8 earthquake 41 km N of La Ligua, Chile

Wednesday, August 10, 2016, 08:20:18 UTC · 32.080°S, 71.259°W

A magnitude 4.8 earthquake struck 41 km N of La Ligua, Chile on Wednesday, August 10, 2016, 08:20:18 UTC, at a depth of 84.0 km (intermediate). USGS received 9 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M5.0 on August 8, 2016.

Magnitude: 4.8; Light · mwr
Depth: 84 km; Intermediate
Felt reports: 9; Max intensity IV
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

139 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: intermediate

84 km

Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.

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
San Antonio, Valparaíso, Chile	IV · Light	1	191 km
Villa Alemana, Valparaíso, Chile	IV · Light	1	136 km
Los Andes, Valparaíso, Chile	III · Weak	1	135 km
Santiago, Metropolitana, Chile	III · Weak	1	185 km
Calera, Valparaíso, Chile	III · Weak	1	116 km
Valparaíso, Valparaíso, Chile	II · Weak	1	140 km
Machalí, Libertador General Bernardo OʿHiggins, Chile	II · Weak	1	254 km
Puente Alto, Metropolitana, Chile	II · Weak	1	201 km
Viña del Mar, Valparaíso, Chile	II · Weak	1	135 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on September 7, 2016. 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.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 946 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 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 · 244 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
1944M6.9
San Juan Province
15 Jan 1944 · 270 km away · intensity IX
10,000 deaths$100 million damage
1906M8.2
South Central
17 Aug 1906 · 124 km away · intensity XI
4,000 deaths$100 million damagetsunami
1965M7.3
Central
28 Mar 1965 · 36 km away
400 deaths$125 million damage
1920M6.7
Mendoza
17 Dec 1920 · 269 km away · intensity VIII
400 deathsSevere damage ($5–24M)
1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 124 km away · intensity VIII
180 deaths$1.5 billion damagetsunami

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

Nearby trackers