M6.6 earthquake 74 km WSW of San Antonio de los Cobres, Argentina

Friday, August 25, 2006, 00:44:46 UTC · 24.403°S, 67.028°W

A magnitude 6.6 earthquake struck 74 km WSW of San Antonio de los Cobres, Argentina on Friday, August 25, 2006, 00:44:46 UTC, at a depth of 184.0 km (intermediate). USGS received 12 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M6.8 on November 17, 2005.

Magnitude: 6.6; Strong · mwb
Depth: 184 km; Intermediate
Felt reports: 12; Max intensity IV
Est. shaking: —; No ShakeMap
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 100 km aftershock search area

In context

How big was it, and why here?

Energy released

120 kilotons of TNT

That is about 8 times the Hiroshima bomb. It released about 251 times the energy of a magnitude 5.0.

Tectonic setting

321 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

184 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
Antofagasta, Antofagasta, Chile	II · Weak	10	397 km
Taltal, Antofagasta, Chile	IV · Light	1	408 km
Copiapó, Atacama, Chile	III · Weak	1	501 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 100 km

USGS lists 27 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.1 on September 4, 2006. 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 363 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 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 33 recorded deaths. The most severe:

1930M6.1
La Poma
24 Dec 1930 · 180 km away · intensity VIII
31 deathsSevere damage ($5–24M)
1971M6.3
Catalina, Antofagasta
17 Jun 1971 · 251 km away · intensity V
1 deathModerate damage ($1–5M)
1950M8.0
Chile-Argentina
9 Dec 1950 · 111 km away · intensity VII
1 death
1844M6.5
Salta, Jujuy, Tucuman
19 Oct 1844 · 123 km away · intensity VII
Severe damage ($5–24M)
1948M6.9
Salta
25 Aug 1948 · 254 km away · intensity IX
Moderate damage ($1–5M)
1959M6.6
Salta
12 May 1959 · 262 km away · intensity VIII
Moderate damage ($1–5M)

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

Nearby trackers