M4.2 earthquake 41 km NW of Ovalle, Chile

Thursday, January 21, 2016, 13:36:09 UTC · 30.390°S, 71.553°W

A magnitude 4.2 earthquake struck 41 km NW of Ovalle, Chile on Thursday, January 21, 2016, 13:36:09 UTC, at a depth of 42.3 km (shallow).

Magnitude: 4.2; Light · mwr
Depth: 42 km; Shallow
Felt reports: 0; Max intensity I
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

30 tons of TNT

That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.

Tectonic setting

101 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

42 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

No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.

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 21 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M6.3 on February 10, 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 725 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 47 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 5,302 recorded deaths. The most severe:

1906M8.2
South Central
17 Aug 1906 · 293 km away · intensity XI
4,000 deaths$100 million damagetsunami
1922M8.5
Atacama
11 Nov 1922 · 286 km away · intensity XI
700 deathsSevere damage ($5–24M)tsunami
1965M7.3
Central
28 Mar 1965 · 226 km away
400 deaths$125 million damage
1971M7.8
Central
9 Jul 1971 · 237 km away · intensity IX
83 deaths$236 million damagetsunami
1822M8.5
Valparaiso, Quillota, Concon, Aconcagua
20 Nov 1822 · 293 km away · intensity XI
72 deathsExtreme damage ($25M+)tsunami
2015M8.3
Central
16 Sep 2015 · 132 km away · intensity IX
15 deaths$600 million damagetsunami

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

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