Reviewed by USGSTonga30y ago
M4.2 earthquake 236 km W of Haveluloto, Tonga
Friday, August 16, 1996, 11:28:20 UTC · 21.338°S, 177.486°W
A magnitude 4.2 earthquake struck 236 km W of Haveluloto, Tonga on Friday, August 16, 1996, 11:28:20 UTC, at a depth of 400.0 km (deep).
- Magnitude
- 4.2
- Light · mb
- Depth
- 400 km
- Deep
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
30 tons of TNT
That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.
Tectonic setting
111 km
from the nearest mapped plate boundary, between the Tonga and Australian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: deep
400 km
Deep earthquakes (over 300 km) happen deep inside subducting plates. They rarely cause damage, but can be felt faintly over very large distances.
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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 1,053 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.0TongaJanuary 4, 1903 · 298 km NE of this epicenter
- 7.8159 km W of Pangai, TongaDecember 14, 1950 · 247 km NE of this epicenter
- 7.8Fiji regionJanuary 1, 1919 · 233 km N of this epicenter
- 7.5262 km WNW of Haveluloto, TongaMay 21, 1962 · 139 km N of this epicenter
- 7.4Fiji regionSeptember 28, 1957 · 126 km NW of this epicenter
- 7.4Fiji regionAugust 5, 1996 · 112 km NW of this epicenter
- 7.3227 km WNW of Haveluloto, TongaApril 16, 1937 · 84 km N of this epicenter
- 7.3Fiji regionMay 25, 1944 · 204 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 8 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1 recorded deaths. The most severe:
- 1977M7.2
Tonga Trench
22 Jun 1977 · 237 km away · intensity IV
1 death$1 million damagetsunami
- 1937M8.1
Fiji Islands
16 Apr 1937 · 53 km away
- 1903M8.0
Tonga Islands
4 Jan 1903 · 298 km away
- 1919M7.8
Fiji Islands
1 Jan 1919 · 233 km away
tsunami
- 1950M7.7
Tonga Islands
14 Dec 1950 · 256 km away · intensity VI
- 1957M7.5
Fiji Islands
28 Sep 1957 · 148 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.