Reviewed by USGS22y ago
M4.7 earthquake southeast of the Loyalty Islands
Saturday, April 17, 2004, 02:38:29 UTC · 22.266°S, 170.006°E
A magnitude 4.7 earthquake struck southeast of the Loyalty Islands on Saturday, April 17, 2004, 02:38:29 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M5.4 on April 16, 2004.
- Magnitude
- 4.7
- Light · mb
- Depth
- 10 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
169 tons of TNT
That is about 1/89 of the Hiroshima bomb. A magnitude 5.0 releases about 3 times more energy.
Tectonic setting
18 km
from the nearest mapped plate boundary, between the New Hebrides and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
10 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 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M6.3 on May 7, 2004. 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 847 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11920 Vanuatu EarthquakeSeptember 20, 1920 · 299 km NW of this epicenter
- 7.828 km ESE of Isangel, VanuatuJune 16, 1910 · 300 km N of this epicenter
- 7.7249 km E of Vao, New CaledoniaMay 16, 1995 · 83 km S of this epicenter
- 7.6274 km ESE of Tadine, New CaledoniaMarch 16, 1928 · 41 km E of this epicenter
- 7.5southeast of the Loyalty IslandsJanuary 4, 1998 · 93 km E of this epicenter
- 7.3201 km ESE of Tadine, New CaledoniaDecember 27, 2003 · 37 km NW of this epicenter
- 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 168 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 26 recorded deaths. The most severe:
- 1875M8.1
Loyalty Islands: Lifou Island
28 Mar 1875 · 296 km away
26 deathsSevere damage ($5–24M)tsunami
- 1901M7.9
Loyalty Islands
9 Aug 1901 · 30 km away
Moderate damage ($1–5M)tsunami
- 1920M8.1
Loyalty Islands
20 Sep 1920 · 299 km away
Limited damage (under $1M)tsunami
- 1995M7.7
Noumea; Vanuatu: Port-Vila
16 May 1995 · 83 km away · intensity III
tsunami
- 1910M7.5
Vanuatu Islands
1 Jun 1910 · 273 km away
- 1928M7.5
Loyalty Islands
16 Mar 1928 · 59 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.