M5.6 earthquake 197 km SSW of Vaini, Tonga
A magnitude 5.6 earthquake struck 197 km SSW of Vaini, Tonga on Thu, Feb 23, 1978, 8:37 AM GMT+13 (19:37 UTC), 85 km (53 mi) below the surface.
A larger quake followed: M5.7 177 km SSW of ‘Ohonua, Tonga. This one was a foreshock.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 5.6 (mb), moderate
- Local time
- UTC
- 1978-02-22 19:37:17 UTC
- Depth
- 85.0 km (52.8 mi), intermediate-depth
- Epicenter
- 22.698° S, 176.207° W
- Region
- Tonga
- Tsunami flag
- No
- Status
- Reviewed by a seismologist
Did you feel it?
No one has reported feeling this quake to the USGS.
How well it is located
Reviewed by a seismologist.
- Depth from
- OPERATOR_ASSIGNED
- Stations used
- 116
Nearest places
Distance and direction from each place to the epicenter, with its forecast.
Nearby
Within 100 km, magnitude 2.6 and up: 3 in the 60 days after this one and 2 in the 30 days before it.
After
- 4.8159 km SSW of ‘Ohonua, Tonga · 17727 days ago · 95 km deep · 86 km away
- 5.7177 km SSW of ‘Ohonua, Tonga · 17726 days ago · 33 km deep · 90 km away
- 4.7148 km SSW of ‘Ohonua, Tonga · 17704 days ago · 33 km deep · 100 km away
Before
Earthquakes todayTonga earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event usp0000t3j (also filed as gcmtb022278c, gcmt19780222193717, iscgem686863). Read Sun, Sep 27, 2026, 6:51 AM UTC.