Reviewed by USGSEcuador55y ago
M7.4 earthquake 98 km ESE of Sucúa, Ecuador
Tuesday, July 27, 1971, 02:02:49 UTC · 2.848°S, 77.379°W
A magnitude 7.4 earthquake struck 98 km ESE of Sucúa, Ecuador on Tuesday, July 27, 1971, 02:02:49 UTC, at a depth of 113.3 km (intermediate). It is the strongest earthquake within 300 km since an M7.5 on September 28, 1906.
- Magnitude
- 7.4
- Major · mw
- Depth
- 113 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VII
- Very strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
2.0 megatons of TNT
That is about 135 times the Hiroshima bomb. It released about 4,266 times the energy of a magnitude 5.0.
Tectonic setting
197 km
from the nearest mapped plate boundary, between the North Andes and South American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
113 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 200 km
USGS has not published any M2.5+ earthquake within 200 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 38 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.516 km W of Barranca, PeruSeptember 28, 1906 · 227 km S of this epicenter
- 6.737 km E of Palora, EcuadorMay 17, 1971 · 138 km N of this epicenter
- 6.655 km ENE of Macas, EcuadorMay 10, 1963 · 78 km N of this epicenter
- 6.6119 km E of Macas, EcuadorJuly 28, 1961 · 73 km NE of this epicenter
- 6.558 km E of Puyo, EcuadorSeptember 17, 1965 · 157 km N of this epicenter
- 6.542 km SE of Cayambe, EcuadorMay 11, 1955 · 296 km N of this epicenter
- 6.522 km NE of Baños, EcuadorAugust 5, 1949 · 207 km NW of this epicenter
- 6.3128 km ESE of Palora, EcuadorJune 12, 1942 · 102 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 47,052 recorded deaths. The most severe:
- 1797M8.3
Riobamba, Quito, Cuzco; Peru; Colombia
4 Feb 1797 · 197 km away · intensity XI
40,000 deathsExtreme damage ($25M+)tsunami
- 1949M6.5
Tungurahua
5 Aug 1949 · 207 km away
6,000 deaths$8 million damage
- 1757M7.0
Cotopaxi,Tungurahua, Latacunga
22 Feb 1757 · 256 km away · intensity IX
1,000 deathsSevere damage ($5–24M)
- 1924M6.9
Ecuador
3 Mar 1924 · 194 km away
40 deathsLimited damage (under $1M)
- 1960
Ecuador
30 Jul 1960 · 234 km away
11 deathsLimited damage (under $1M)
- 1971M6.3
Guayaquil
27 Jul 1971 · 17 km away · intensity VII
1 deathModerate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.