M6.3 earthquake 132 km E of Pangai, Tonga
A magnitude 6.3 earthquake struck 132 km E of Pangai, Tonga on Thu, Oct 8, 1987, 4:20 PM GMT+13 (03:20 UTC), 40 km (25 mi) below the surface.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 6.3 (Mw, moment), strong
- Magnitude from
- USGS National Earthquake Information Center
- Local time
- UTC
- 1987-10-08 03:20:45 UTC
- Depth
- 40.4 km (25.1 mi), shallow
- Epicenter
- 19.599° S, 173.111° 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 |
|---|---|---|---|
| 6.3 | Mw, moment | USGS National Earthquake Information Center | Preferred · Reviewed |
| 6.29 | Mw, moment | ISC-GEM global catalog | Final · ±0.1 |
| 6.3 | Mwc, centroid moment | Global CMT project | Preliminary |
What happened
The USGS’s account of the effects of this earthquake.
FAULT PLANE SOLUTION: P-Waves NP1:Strike=198 Dip=68 Slip=90 NP2:Strike=18 Dip=22 Slip=90 Principal Axes: (T) Plg=67 Azm=108 (P) Plg=23 Azm=288 Comment: The focal mechanism is poorly controlled and corresponds to reverse faulting. The preferred fault plane is not determined. CENTROID, MOMENT TENSOR (HRV) Data Used: GDSN L.P.B.: 17S, 48C M.W.: 14S, 31C Centroid Location: Origin Time 03:20:53.4 0.2 Lat 19.72S 0.02 Lon 173.00W 0.01 Dep 49.3 0.8 Half-duration 5.5 Moment Tensor; Scale 10**18 Nm Mrr=2.29 0.03 Mtt=0.81 0.03 Mff=-3.10 0.03 Mrt=1.30 0.05 Mrf=-0.20 0.05 Mtf=-1.21 0.03 Principal Axes: (T) Val=3.15 Plg=57 Azm=14 (N) Val=0.30 Plg=33 Azm=197 (P) Val=-3.45 Plg=2 Azm=106 Best Double Couple:Mo=3.3*10**18 NP1:Strike=167 Dip=52 Slip=46 NP2:Strike=44 Dip=55 Slip=132
From the USGS event page for usp000392g. 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
Nearest places
Distance and direction from each place to the epicenter, with its forecast.
Nearby
Within 100 km, magnitude 3.3 and up: 2 in the 60 days after this one and 0 in the 30 days before it.
After
Earthquakes todayTonga earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event usp000392g (also filed as gcmtc100887b, gcmt19871008032044, iscgem454913). Read Thu, Oct 1, 2026, 4:36 PM UTC.