Reviewed by USGS30y ago
M4.9 earthquake south of the Fiji Islands
Thursday, April 18, 1996, 03:47:58 UTC · 24.204°S, 176.948°W
A magnitude 4.9 earthquake struck south of the Fiji Islands on Thursday, April 18, 1996, 03:47:58 UTC, at a depth of 107.7 km (intermediate). It is the strongest earthquake within 300 km since an M5.0 on April 17, 1996.
- Magnitude
- 4.9
- Light · mb
- Depth
- 108 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
338 tons of TNT
That is about 1/45 of the Hiroshima bomb. A magnitude 5.0 releases about 1 times more energy.
Tectonic setting
18 km
from the nearest mapped plate boundary, between the Kermadec and Tonga plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: intermediate
108 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 lists 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.3 on May 9, 1996. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 764 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8south of TongaOctober 11, 1975 · 200 km SE of this epicenter
- 7.6south of the Fiji IslandsDecember 18, 1963 · 62 km S of this epicenter
- 7.3south of the Fiji IslandsJanuary 20, 1970 · 192 km S of this epicenter
- 7.2south of the Fiji IslandsNovember 24, 1960 · 88 km SE of this epicenter
- 7.2south of TongaOctober 10, 1977 · 241 km SE of this epicenter
- 7.2south of the Fiji IslandsApril 16, 1996 · 18 km NW of this epicenter
- 7.2south of the Fiji IslandsJuly 11, 1992 · 243 km NW of this epicenter
- 7.2157 km WSW of Haveluloto, TongaOctober 30, 1986 · 280 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 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 · 182 km away · intensity IV
1 death$1 million damagetsunami
- 1975M7.8
S Of Tonga
11 Oct 1975 · 200 km away
- 1982M7.7
Tonga Trench
19 Dec 1982 · 110 km away
tsunami
- 1963M7.5
Tonga Trench
18 Dec 1963 · 75 km away
tsunami
- 1977M7.2
Tonga Trench
10 Oct 1977 · 241 km away
tsunami
- 1956M7.0
Tonga Islands
10 Jan 1956 · 263 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.