Reviewed by USGSNew Zealand59y ago
M6.9 earthquake in Kermadec Islands, New Zealand
Monday, May 20, 1968, 20:05:52 UTC · 30.754°S, 178.129°W
A magnitude 6.9 earthquake struck in Kermadec Islands, New Zealand on Monday, May 20, 1968, 20:05:52 UTC, at a depth of 60.1 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on May 20, 1968.
- Magnitude
- 6.9
- Strong · mw
- Depth
- 60 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
349 kilotons of TNT
That is about 23 times the Hiroshima bomb. It released about 733 times the energy of a magnitude 5.0.
Tectonic setting
112 km
from the nearest mapped plate boundary, between the Kermadec and Australian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
60 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 4 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M6.4 on May 30, 1968. 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 170 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.21917 Kermadec Islands, New Zealand EarthquakeMay 1, 1917 · 149 km E of this epicenter
- 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 104 km N of this epicenter
- 7.3Kermadec Islands regionSeptember 14, 1959 · 231 km NE of this epicenter
- 7.3Kermadec Islands, New ZealandMarch 26, 1963 · 95 km NE of this epicenter
- 7.2Kermadec Islands, New ZealandAugust 2, 1941 · 120 km NE of this epicenter
- 7.2Kermadec Islands, New ZealandApril 17, 1919 · 23 km NE of this epicenter
- 7.1Kermadec Islands, New ZealandJune 29, 1910 · 100 km E of this epicenter
- 7.1Kermadec Islands, New ZealandSeptember 16, 1941 · 184 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1968M7.3
S Of, Raoul
25 Jul 1968 · 26 km away
Limited damage (under $1M)tsunami
- 1917M8.0
Kermadec Islands
1 May 1917 · 204 km away
tsunami
- 1959M7.7
Kermadec Islands
14 Sep 1959 · 273 km away
- 1943M7.6
S Of
14 Sep 1943 · 137 km away
- 1917M7.5
S Of
16 Nov 1917 · 204 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.