M5.8 earthquake 280 km SW of Vaini, Tonga
A magnitude 5.8 earthquake struck 280 km SW of Vaini, Tonga on Wed, Aug 18, 2021, 6:24 AM GMT+13 (17:24 UTC), 157 km (98 mi) below the surface.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 5.8 (mww), moderate
- Local time
- UTC
- 2021-08-17 17:24:49 UTC
- Depth
- 157.0 km (97.6 mi), intermediate-depth
- Epicenter
- 23.037° S, 177.039° W
- Region
- Tonga
- Felt reports
- 2
- Strongest shaking
- III, weak shaking
- PAGER alert
- Green
- Tsunami flag
- No
- Status
- Reviewed by a seismologist
Shaking
The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.
- Strongest estimated
- III, weak shaking
- Peak ground acceleration
- 0.3% of gravity
- Peak ground velocity
- -2.1 cm/s
- Map
- Automatic
Did you feel it?
2 people reported to the USGS what they felt; the strongest reported shaking was III, weak shaking.
Estimated impact
The USGS PAGER system estimates deaths and economic losses from the shaking and the population and buildings exposed to it.
- Alert level
- Green: little or no damage or loss of life expected
| Range | Chance |
|---|---|
| Under 1 | 65% |
| 1 to 10 | 30% |
| 10 to 100 | 4% |
| 100 to 1,000 | Under 1% |
| 1,000 to 10,000 | Under 1% |
| 10,000 to 100,000 | Under 1% |
| 100,000 to 10,000,000 | Under 1% |
| Range, million USD | Chance |
|---|---|
| Under 1 | 65% |
| 1 to 10 | 30% |
| 10 to 100 | 4% |
| 100 to 1,000 | Under 1% |
| 1,000 to 10,000 | Under 1% |
| 10,000 to 100,000 | Under 1% |
| 100,000 to 10,000,000 | Under 1% |
Fault motion and ground failure
How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.
- Faulting
- Strike-slip
- Moment magnitude
- 5.8 Mww
- Nodal plane 1
- Strike 274°, dip 9°, rake -28°
- Nodal plane 2
- Strike 31°, dip 86°, rake -98°
How well it is located
Reviewed by a seismologist.
- Location uncertainty
- About 8.6 km horizontally, 1.8 km in depth
- Magnitude uncertainty
- ±0.05
- Depth from
- From modeling of broad-band P waveforms
- Station coverage gap
- 22°
- Stations used
- 181
Nearest places
Distance and direction from each place to the epicenter, with its forecast.
Nearby
Within 100 km, magnitude 2.8 and up: 3 in the 60 days after this one and 3 in the 30 days before it.
After
- 4.7south of the Fiji Islands · 1868 days ago · 160 km deep · 38 km away
- 4.6south of the Fiji Islands · 1843 days ago · 349 km deep · 84 km away
- 4.1south of the Fiji Islands · 1825 days ago · 149 km deep · 77 km away
Before
Earthquakes todayTonga earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event us6000f7ki (also filed as usauto6000f7ki, pt21229001, iscgem620993291). Read Wed, Sep 30, 2026, 9:36 AM UTC.