M7.7 earthquake 56 km NW of Valdez, Ecuador

Wednesday, December 12, 1979, 07:59:03 UTC · 1.598°N, 79.358°W

A magnitude 7.7 earthquake struck 56 km NW of Valdez, Ecuador on Wednesday, December 12, 1979, 07:59:03 UTC, at a depth of 24.0 km (shallow). It is the strongest earthquake within 300 km since an M7.8 on May 14, 1942.

Magnitude: 7.7; Major · ms
Depth: 24 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VIII; Severe (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

5.4 megatons of TNT

That is about 355 times the Hiroshima bomb. It released about 11,220 times the energy of a magnitude 5.0.

Tectonic setting

71 km

from the nearest mapped plate boundary, between the Nazca and North Andes plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

24 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 200 km

USGS lists 78 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.8 on December 13, 1979. 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 53 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 27 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 73,285 recorded deaths. The most severe:

1868M7.7
Guayaquil,Ibarra; Colombia: San Pablo
16 Aug 1868 · 194 km away · intensity X
70,000 deathsExtreme damage ($25M+)
1906M8.8
Off Coast
31 Jan 1906 · 72 km away · intensity IX
1,000 deathsSevere damage ($5–24M)tsunami
1757M7.0
Cotopaxi,Tungurahua, Latacunga
22 Feb 1757 · 290 km away · intensity IX
1,000 deathsSevere damage ($5–24M)
1979M8.1
Off Shore, Pacific Ocean
12 Dec 1979 · 10 km away · intensity IX
600 deaths$8 million damagetsunami
1923M6.2
Ipiales
14 Dec 1923 · 193 km away · intensity IX
300 deathsModerate damage ($1–5M)
1936M5.6
Colombia
9 Jan 1936 · 203 km away · intensity VII
250 deathsModerate damage ($1–5M)

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

Nearby trackers