Reviewed by USGSNew Zealand47y ago
M7.4 earthquake 180 km W of Riverton, New Zealand
Friday, October 12, 1979, 10:25:22 UTC · 46.675°S, 165.707°E
A magnitude 7.4 earthquake struck 180 km W of Riverton, New Zealand on Friday, October 12, 1979, 10:25:22 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M7.5 on September 1, 1945.
- Magnitude
- 7.4
- Major · ms
- 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: 200 km aftershock search area
In context
How big was it, and why here?
Energy released
1.9 megatons of TNT
That is about 126 times the Hiroshima bomb. It released about 3,981 times the energy of a magnitude 5.0.
Tectonic setting
50 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 4 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.5 on October 12, 1979. 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 26 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 · 40 km SE of this epicenter
- 7.0Auckland Islands, New Zealand regionSeptember 12, 1964 · 280 km S of this epicenter
- 7.015 km WNW of Te Anau, New ZealandDecember 16, 1938 · 202 km NE of this epicenter
- 7.0Auckland Islands, New Zealand regionFebruary 22, 1936 · 298 km S of this epicenter
- 6.8off the west coast of the South Island of New ZealandJanuary 12, 1954 · 232 km S of this epicenter
- 6.7off the west coast of the South Island of New ZealandJanuary 13, 1954 · 228 km S of this epicenter
- 6.762 km WNW of Te Anau, New ZealandAugust 2, 1943 · 187 km NE of this epicenter
- 6.686 km N of Te Anau, New ZealandMay 4, 1976 · 269 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 2 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1826M8.0
Fjordland
1826 · 115 km away
- 1979M7.5
W Of North Island
12 Oct 1979 · 0 km away · intensity V
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.