M6.6 earthquake 147 km SW of Hihifo, Tonga
A magnitude 6.6 earthquake struck 147 km SW of Hihifo, Tonga on Tue, May 31, 1983, 1:59 PM GMT-12 (01:59 UTC), 180 km (112 mi) below the surface.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 6.6 (Mw, moment), strong
- Magnitude from
- USGS National Earthquake Information Center
- Local time
- UTC
- 1983-06-01 01:59:54 UTC
- Depth
- 179.6 km (111.6 mi), intermediate-depth
- Epicenter
- 17.038° S, 174.605° W
- Region
- Tonga
- Tsunami flag
- No
- Status
- Reviewed by a seismologist
Magnitude estimates
Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.
| Mag. | Scale | Computed by | Notes |
|---|---|---|---|
| 6.6 | Mw, moment | USGS National Earthquake Information Center | Preferred · Reviewed |
| 6.51 | Mw, moment | ISC-GEM global catalog | Final · ±0.1 |
| 6.5 | Mwc, centroid moment | Global CMT project | Preliminary |
What happened
The USGS’s account of the effects of this earthquake.
Felt (II) at Apia, Samoa Islands. [FS]. FAULT PLANE SOLUTION: P-WAVES NP1:STRIKE=48;DIP=68;SLIP=-90 NP2:STRIKE=228;DIP=22;SLIP=-90 PRINCIPAL AXES: (T) PLG=23; AZM=138 (P) PLG=67; AZM=318 COMMENT: Poorly controlled normal fault type mechanism. NP1 designated as the fault plane. MOMENT TENSOR SOLUTION NO OF STA 12 SCALE 10**25 D-CM DEPTH 182 PRINCIPAL AXES: (T) VAL=8.57; PLG=14; AZM=123 (N) VAL=-0.55; PLG=12; AZM=216 (P) VAL=-8.02; PLG=71; AZM=344 BEST DOUBLE COUPLE:Mo=8.3*10**25 NP1:STRIKE=197;DIP=32;SLIP=-112 NP2:STRIKE=43;DIP=60;SLIP=-76 CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME B060183B DATA USED: GDSN L.P. BODY WAVES: 24S, 61C, T=45 CENTROID LOCATION: ORIGIN TIME 2: 0: 1.9 0.2 LAT 16.93S 0.02;LON 174.39W 0.02 DEP 185.7 0.7;HALF-DURATION 6.8 MOMENT TENSOR; SCALE 10**25 D-CM MRR=-5.42 0.10; MTT=1.79 0.15 MFF=3.63 0.15; MRT=-3.15 0.11 MRF=-3.78 0.11; MTF=2.30 0.14 PRINCIPAL AXES: 1.(T) VAL=7.11;PLG=21;AZM=126 2.(N) 0.25; 3; 217 3.(P) -7.36; 68; 313 BEST DOUBLE COUPLE:M0=7.2*10**25 NP1:STRIKE=211;DIP=24;SLIP=-97 NP2:Strike=38;Dip=66;Slip=-87
From the USGS event page for usp0001vuc. U.S. Geological Survey text and figures are in the public domain.
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
- CONSTRAINED_BY_DEPTH_PHASES
Nearby
Within 100 km, magnitude 3.6 and up: 4 in the 60 days after this one and 1 in the 30 days before it.
After
- 4.9138 km SW of Hihifo, Tonga · 15831 days ago · 153 km deep · 9 km away
- 4.6101 km S of Hihifo, Tonga · 15828 days ago · 35 km deep · 100 km away
- 4.8137 km SW of Hihifo, Tonga · 15813 days ago · 286 km deep · 40 km away
- 4.6135 km SW of Hihifo, Tonga · 15779 days ago · 33 km deep · 13 km away
Before
Earthquakes todayTonga earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event usp0001vuc (also filed as gcmtb060183b, gcmt19830601020000, iscgem573177). Read Sun, Oct 4, 2026, 4:17 PM UTC.