Reviewed by USGSNew Zealand82y ago
M7.5 earthquake 173 km WSW of Riverton, New Zealand
Saturday, September 1, 1945, 22:44:11 UTC · 46.990°S, 165.955°E
A magnitude 7.5 earthquake struck 173 km WSW of Riverton, New Zealand on Saturday, September 1, 1945, 22:44:11 UTC, at a depth of 20.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 7.5
- Major · mw
- Depth
- 20 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 earthquake
In context
How big was it, and why here?
Energy released
2.7 megatons of TNT
That is about 178 times the Hiroshima bomb. It released about 5,623 times the energy of a magnitude 5.0.
Tectonic setting
78 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
20 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 has not published any M2.5+ earthquake within 200 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 8 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.015 km WNW of Te Anau, New ZealandDecember 16, 1938 · 217 km NE of this epicenter
- 7.0Auckland Islands, New Zealand regionFebruary 22, 1936 · 274 km SW of this epicenter
- 6.762 km WNW of Te Anau, New ZealandAugust 2, 1943 · 209 km N of this epicenter
- 6.6115 km WNW of Te Anau, New ZealandDecember 16, 1938 · 241 km N of this epicenter
- 6.5248 km SW of Bluff, New ZealandFebruary 15, 1922 · 167 km S of this epicenter
- 6.5off the west coast of the South Island of New ZealandFebruary 22, 1936 · 259 km SW of this epicenter
- 6.280 km WSW of Te Anau, New ZealandApril 20, 1939 · 162 km N of this epicenter
- 6.2Auckland Islands, New Zealand regionAugust 13, 1932 · 263 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 1 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1826M8.0
Fjordland
1826 · 139 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.