Reviewed by USGS38y ago
M6.6 earthquake southeast of the Loyalty Islands
Saturday, July 23, 1988, 14:25:36 UTC · 22.127°S, 174.900°E
A magnitude 6.6 earthquake struck southeast of the Loyalty Islands on Saturday, July 23, 1988, 14:25:36 UTC, at a depth of 18.5 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on August 25, 1926.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 19 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
120 kilotons of TNT
That is about 8 times the Hiroshima bomb. It released about 251 times the energy of a magnitude 5.0.
Tectonic setting
15 km
from the nearest mapped plate boundary, between the Australian and Conway Reef plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
19 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 3 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.4 on July 24, 1988. 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 65 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.0southeast of the Loyalty IslandsAugust 25, 1926 · 296 km W of this epicenter
- 6.7southeast of the Loyalty IslandsJune 14, 1905 · 263 km SW of this epicenter
- 6.6Vanuatu regionNovember 4, 1934 · 38 km NW of this epicenter
- 6.5southeast of the Loyalty IslandsNovember 4, 1934 · 39 km W of this epicenter
- 6.5Vanuatu regionMarch 10, 1948 · 164 km NW of this epicenter
- 6.5south of the Fiji IslandsApril 20, 1938 · 25 km SE of this epicenter
- 6.5Vanuatu regionJune 24, 1987 · 172 km NW of this epicenter
- 6.5Vanuatu regionJanuary 10, 1948 · 248 km NW of this epicenter