Reviewed by USGS46y ago
M7.6 earthquake off the west coast of the South Island of New Zealand
Monday, May 25, 1981, 05:25:14 UTC · 48.786°S, 164.357°E
A magnitude 7.6 earthquake struck off the west coast of the South Island of New Zealand on Monday, May 25, 1981, 05:25:14 UTC, at a depth of 33.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 7.6
- Major · ms
- Depth
- 33 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- IV
- Light (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
3.8 megatons of TNT
That is about 252 times the Hiroshima bomb. It released about 7,943 times the energy of a magnitude 5.0.
Tectonic setting
17 km
from the nearest mapped plate boundary, between the Pacific and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
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 200 km
USGS lists 8 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.7 on May 30, 1981. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 5.3Auckland Islands, New Zealand region45y ago · 50 km SE of this epicenter
- 5.3off the west coast of the South Island of New Zealand45y ago · 35 km NE of this epicenter
- 5.7Auckland Islands, New Zealand region45y ago · 49 km SE of this epicenter
- 5.3off the west coast of the South Island of New Zealand45y ago · 34 km NW of this epicenter
- 4.6Auckland Islands, New Zealand region46y ago · 54 km S of this epicenter
- 4.5Auckland Islands, New Zealand region46y ago · 54 km S of this epicenter
- 4.7Auckland Islands, New Zealand region46y ago · 56 km S of this epicenter
- 5.1Auckland Islands, New Zealand region46y ago · 65 km S of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 36 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.5173 km WSW of Riverton, New ZealandSeptember 1, 1945 · 233 km NE of this epicenter
- 7.4180 km W of Riverton, New ZealandOctober 12, 1979 · 256 km NE of this epicenter
- 7.0Auckland Islands, New Zealand regionSeptember 12, 1964 · 27 km S of this epicenter
- 7.0Auckland Islands, New Zealand regionJanuary 5, 1955 · 180 km SW of this epicenter
- 7.0Auckland Islands, New Zealand regionFebruary 22, 1936 · 43 km S of this epicenter
- 6.8off the west coast of the South Island of New ZealandJanuary 12, 1954 · 41 km E of this epicenter
- 6.7Auckland Islands, New Zealand regionMarch 18, 1961 · 139 km SW of this epicenter
- 6.7off the west coast of the South Island of New ZealandJanuary 13, 1954 · 68 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 3 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1926M7.9
Macquarie Island: North Of
3 Oct 1926 · 247 km away
- 1981M7.6
W Of North Island
25 May 1981 · 0 km away
tsunami
- 1979M7.5
W Of North Island
12 Oct 1979 · 256 km away · intensity V
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.