M5.5 earthquake 27 km NNW of Illapel, Chile

Monday, December 7, 2015, 07:51:11 UTC · 31.398°S, 71.262°W

A magnitude 5.5 earthquake struck 27 km NNW of Illapel, Chile on Monday, December 7, 2015, 07:51:11 UTC, at a depth of 49.5 km (shallow). USGS received 11 “Did You Feel It?” reports, with a maximum reported intensity of V (moderate). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M5.6 on November 28, 2015.

Magnitude: 5.5; Moderate · mwr
Depth: 50 km; Shallow
Felt reports: 11; Max intensity V
Est. shaking: IV; Light (ShakeMap)
PAGER alert: Green; Impact estimate
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 75 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

3 kilotons of TNT

That is about 1/6 of the Hiroshima bomb. It released about 6 times the energy of a magnitude 5.0.

Tectonic setting

133 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

50 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
Santiago, Metropolitana, Chile	III · Weak	5	241 km
Illapel, Coquimbo, Chile	V · Moderate	1	56 km
Valparaíso, Valparaíso, Chile	III · Weak	1	191 km
Viña del Mar, Valparaíso, Chile	III · Weak	1	187 km
Quilpué, Valparaíso, Chile	III · Weak	1	189 km
Vicuña, Coquimbo, Chile	II · Weak	1	167 km
Iquique, Tarapacá, Chile	II · Weak	1	1243 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 populated area was estimated to feel noticeable shaking.

After the main event

Aftershocks within 75 km

USGS lists 12 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.6 on December 23, 2015. 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 861 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 57 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 29,198 recorded deaths. The most severe:

1861
Mendoza, San Luiz
20 Mar 1861 · 279 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
1944M6.9
San Juan Province
15 Jan 1944 · 263 km away · intensity IX
10,000 deaths$100 million damage
1906M8.2
South Central
17 Aug 1906 · 191 km away · intensity XI
4,000 deaths$100 million damagetsunami
1965M7.3
Central
28 Mar 1965 · 112 km away
400 deaths$125 million damage
1920M6.7
Mendoza
17 Dec 1920 · 276 km away · intensity VIII
400 deathsSevere damage ($5–24M)
1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 197 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