Reviewed by USGSVanuatu27y ago
M4.1 earthquake 94 km ENE of Norsup, Vanuatu
Thursday, December 23, 1999, 15:46:09 UTC · 15.676°S, 168.178°E
A magnitude 4.1 earthquake struck 94 km ENE of Norsup, Vanuatu on Thursday, December 23, 1999, 15:46:09 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 4.1
- Light · mb
- Depth
- 33 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
21 tons of TNT
That is about 1/707 of the Hiroshima bomb. A magnitude 5.0 releases about 22 times more energy.
Tectonic setting
192 km
from the nearest mapped plate boundary, between the New Hebrides and Australian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
33 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.0 on December 23, 1999. 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 1,093 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.745 km NNE of Port-Olry, VanuatuMay 20, 1965 · 155 km NW of this epicenter
- 7.631 km S of Luganville, VanuatuAugust 11, 1965 · 108 km W of this epicenter
- 7.581 km NW of Port-Olry, VanuatuDecember 28, 1973 · 216 km NW of this epicenter
- 7.592 km ESE of Lakatoro, VanuatuNovember 26, 1999 · 83 km S of this epicenter
- 7.447 km WSW of Norsup, VanuatuNovember 9, 1910 · 141 km SW of this epicenter
- 7.443 km W of Norsup, VanuatuAugust 13, 1965 · 136 km W of this epicenter
- 7.3207 km E of Sola, VanuatuFebruary 19, 1905 · 221 km NE of this epicenter
- 7.363 km S of Port-Vila, VanuatuJuly 23, 1961 · 293 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 27 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 11 recorded deaths. The most severe:
- 1999M7.5
Pentecost
26 Nov 1999 · 83 km away
10 deathsSevere damage ($5–24M)tsunami
- 1971M7.1
Espiritu Santo, Port Vila
27 Oct 1971 · 107 km away · intensity VII
1 deathSevere damage ($5–24M)
- 1965M7.6
Vanuatu Islands
11 Aug 1965 · 106 km away
Moderate damage ($1–5M)tsunami
- 1973M7.5
Espiritu Santo, Luganille
28 Dec 1973 · 217 km away · intensity VII
Moderate damage ($1–5M)
- 1910M7.2
Espiritu Santo
10 Nov 1910 · 259 km away
Moderate damage ($1–5M)tsunami
- 1973M7.2
Luganville, Lamap
29 Dec 1973 · 150 km away · intensity VIII
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.