Reviewed by USGS37y ago
M4.9 earthquake southeast of the Loyalty Islands
Sunday, March 18, 1990, 13:25:25 UTC · 22.235°S, 174.088°E
A magnitude 4.9 earthquake struck southeast of the Loyalty Islands on Sunday, March 18, 1990, 13:25:25 UTC, at a depth of 21.3 km (shallow). It is the strongest earthquake within 300 km since an M5.2 on March 7, 1990.
- Magnitude
- 4.9
- Light · mb
- Depth
- 21 km
- Shallow
- 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
3 km
from the nearest mapped plate boundary, between the Conway Reef and New Hebrides plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
21 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
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 M5.1 on April 3, 1990. 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 162 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6south of the Fiji IslandsMarch 3, 1990 · 111 km E of this epicenter
- 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 257 km W of this epicenter
- 7.1southeast of the Loyalty IslandsAugust 17, 1935 · 270 km W of this epicenter
- 7.1southeast of the Loyalty IslandsApril 14, 1906 · 284 km W of this epicenter
- 7.0southeast of the Loyalty IslandsAugust 25, 1926 · 214 km SW of this epicenter
- 7.0southeast of the Loyalty IslandsOctober 5, 1944 · 239 km W of this epicenter
- 7.0southeast of the Loyalty IslandsJuly 6, 1981 · 241 km W of this epicenter
- 6.8south of the Fiji IslandsNovember 7, 1988 · 96 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 2 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1990M7.6
Fiji Islands
3 Mar 1990 · 111 km away
- 1944M7.5
Loyalty Islands
5 Oct 1944 · 217 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.