M4.0 earthquake 119 km ENE of Iquique, Chile

Sunday, August 21, 2005, 21:04:45 UTC · 19.892°S, 69.064°W

A magnitude 4.0 earthquake struck 119 km ENE of Iquique, Chile on Sunday, August 21, 2005, 21:04:45 UTC, at a depth of 111.6 km (intermediate).

Magnitude: 4.0; Light · mb
Depth: 112 km; Intermediate
Felt reports: 0; Did You Feel It?
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

15 tons of TNT

That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.

Tectonic setting

178 km

from the nearest mapped plate boundary, between the Altiplano and South American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: intermediate

112 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

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 7 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on September 19, 2005. 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 464 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 28,108 recorded deaths. The most severe:

1868M8.5
Arica
13 Aug 1868 · 249 km away · intensity XI
25,000 deaths$300 million damagetsunami
1877M8.3
Off North Coast
10 May 1877 · 233 km away · intensity XI
2,385 deaths$2 million damagetsunami
1833M7.7
Peru: Tacna; Chile: Arica
18 Sep 1833 · 274 km away · intensity VIII
700 deathsSevere damage ($5–24M)tsunami
2005M7.7
Tarapaca
13 Jun 2005 · 17 km away
11 deaths$5 million damage
1987M6.9
Arica, Iquique
8 Aug 1987 · 137 km away · intensity VII
5 deaths$1 million damage
1953M7.4
Northern
7 Dec 1953 · 248 km away
3 deaths$7 million damage

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

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