Reviewed by USGS42y ago
M5.0 earthquake in Vanuatu region
Friday, August 31, 1984, 22:06:47 UTC · 18.169°S, 172.160°E
A magnitude 5.0 earthquake struck in Vanuatu region on Friday, August 31, 1984, 22:06:47 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M6.4 on August 31, 1984.
- Magnitude
- 5.0
- Moderate · 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: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
477 tons of TNT
That is about 1/32 of the Hiroshima bomb. Each whole step in magnitude is about 32 times more energy.
Tectonic setting
122 km
from the nearest mapped plate boundary, between the Conway Reef and New Hebrides 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 75 km
USGS lists 1 M2.5+ earthquake within 75 km in the following 30 days; the largest was M4.1 on September 7, 1984. 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 66 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.262 km NE of Isangel, VanuatuJuly 2, 1953 · 285 km W of this epicenter
- 7.1Vanuatu regionJune 29, 1928 · 292 km NW of this epicenter
- 6.986 km NE of Isangel, VanuatuMarch 25, 1912 · 254 km SW of this epicenter
- 6.946 km NE of Isangel, VanuatuJune 30, 1905 · 294 km SW of this epicenter
- 6.6Fiji regionJuly 3, 1959 · 231 km NE of this epicenter
- 6.5286 km E of Port-Vila, VanuatuNovember 3, 1907 · 142 km NW of this epicenter
- 6.5VanuatuJuly 24, 1947 · 253 km W of this epicenter
- 6.5Vanuatu regionJanuary 10, 1948 · 278 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 1 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1910M7.9
Vanuatu Islands
16 Jun 1910 · 295 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.