Reviewed by USGSTonga49y ago
M4.4 earthquake 269 km S of ‘Ohonua, Tonga
Wednesday, July 13, 1977, 14:48:49 UTC · 23.749°S, 175.241°W
A magnitude 4.4 earthquake struck 269 km S of ‘Ohonua, Tonga on Wednesday, July 13, 1977, 14:48:49 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 4.4
- Light · mb
- Depth
- 33 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
60 tons of TNT
That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.
Tectonic setting
4 km
from the nearest mapped plate boundary, between the Kermadec and Tonga plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
33 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 218 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8south of TongaOctober 11, 1975 · 128 km S of this epicenter
- 7.6south of the Fiji IslandsDecember 18, 1963 · 197 km SW of this epicenter
- 7.4south of TongaMarch 18, 1905 · 199 km E of this epicenter
- 7.2south of the Fiji IslandsNovember 24, 1960 · 145 km SW of this epicenter
- 7.0south of TongaJanuary 10, 1956 · 298 km S of this epicenter
- 6.8Tonga regionJune 22, 1977 · 118 km NW of this epicenter
- 6.7south of the Fiji IslandsSeptember 8, 1920 · 135 km SW of this epicenter
- 6.7south of the Fiji IslandsAugust 12, 1967 · 238 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1 recorded deaths. The most severe:
- 1977M7.2
Tonga Trench
22 Jun 1977 · 118 km away · intensity IV
1 death$1 million damagetsunami
- 1975M7.8
S Of Tonga
11 Oct 1975 · 128 km away
- 1963M7.5
Tonga Trench
18 Dec 1963 · 181 km away
tsunami
- 1977M7.2
Tonga Trench
10 Oct 1977 · 235 km away
tsunami
- 1956M7.0
Tonga Islands
10 Jan 1956 · 250 km away
- 1853
Tonga Trench
24 Dec 1853 · 287 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.