Reviewed by USGS42y ago
M6.4 earthquake in Vanuatu region
Friday, August 31, 1984, 15:42:11 UTC · 17.957°S, 172.149°E
A magnitude 6.4 earthquake struck in Vanuatu region on Friday, August 31, 1984, 15:42:11 UTC, at a depth of 29.0 km (shallow). It is the strongest earthquake within 300 km since an M6.6 on July 3, 1959.
- Magnitude
- 6.4
- Strong · mw
- Depth
- 29 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
60 kilotons of TNT
That is about 4 times the Hiroshima bomb. It released about 126 times the energy of a magnitude 5.0.
Tectonic setting
133 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
29 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 100 km
USGS lists 2 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.0 on August 31, 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 50 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 · 294 km SW of this epicenter
- 7.1Vanuatu regionJune 29, 1928 · 271 km NW of this epicenter
- 6.986 km NE of Isangel, VanuatuMarch 25, 1912 · 264 km SW of this epicenter
- 6.6Fiji regionJuly 3, 1959 · 211 km NE of this epicenter
- 6.5286 km E of Port-Vila, VanuatuNovember 3, 1907 · 131 km W of this epicenter
- 6.5VanuatuJuly 24, 1947 · 259 km W of this epicenter
- 6.5Vanuatu regionJanuary 10, 1948 · 298 km SE of this epicenter
- 6.5Vanuatu regionJuly 3, 1959 · 213 km NE of this epicenter