Reviewed by USGSTonga51y ago
M4.4 earthquake 168 km ESE of Hihifo, Tonga
Monday, February 2, 1976, 02:18:44 UTC · 16.257°S, 172.253°W
A magnitude 4.4 earthquake struck 168 km ESE of Hihifo, Tonga on Monday, February 2, 1976, 02:18:44 UTC, at a depth of 104.0 km (intermediate).
- Magnitude
- 4.4
- Light · mb
- Depth
- 104 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
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
6 km
from the nearest mapped plate boundary, between the Tonga and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: intermediate
104 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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.3 on February 4, 1976. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 269 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11919 Tonga EarthquakeApril 30, 1919 · 230 km S of this epicenter
- 8.0The 1917 Samoa-Tonga EarthquakeJune 26, 1917 · 178 km NW of this epicenter
- 7.8146 km ESE of Hihifo, TongaDecember 26, 1975 · 23 km W of this epicenter
- 7.1112 km NNE of Hihifo, TongaApril 14, 1957 · 183 km NW of this epicenter
- 6.9127 km S of Hihifo, TongaMay 8, 1913 · 206 km SW of this epicenter
- 6.8100 km SE of Hihifo, TongaDecember 20, 1914 · 108 km SW of this epicenter
- 6.7127 km NE of Neiafu, TongaNovember 27, 1949 · 196 km SW of this epicenter
- 6.7144 km ENE of Hihifo, TongaOctober 20, 1916 · 84 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 4 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:
- 1917M8.3
Samoa Islands
26 Jun 1917 · 116 km away
2 deathsModerate damage ($1–5M)tsunami
- 1919M8.1
Tonga Islands
30 Apr 1919 · 235 km away
Limited damage (under $1M)tsunami
- 1975M7.8
Samoa Islands
26 Dec 1975 · 23 km away · intensity V
tsunami
- 1957M7.5
Samoa Islands
14 Apr 1957 · 116 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.