Reviewed by USGSNew Zealand96y ago
M6.5 earthquake 105 km SSE of Hastings, New Zealand
Wednesday, April 22, 1931, 00:02:38 UTC · 40.447°S, 177.491°E
A magnitude 6.5 earthquake struck 105 km SSE of Hastings, New Zealand on Wednesday, April 22, 1931, 00:02:38 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.3 on February 13, 1931.
- Magnitude
- 6.5
- Strong · mw
- Depth
- 15 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
74 kilotons of TNT
That is about 5 times the Hiroshima bomb. It released about 155 times the energy of a magnitude 5.0.
Tectonic setting
78 km
from the nearest mapped plate boundary, between the Kermadec and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
15 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 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M6.1 on May 6, 1931. 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 16 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.447 km WSW of Hastings, New ZealandFebruary 2, 1931 · 127 km NW of this epicenter
- 7.340 km E of Waiouru, New ZealandFebruary 13, 1931 · 163 km NW of this epicenter
- 6.9144 km SE of Waipawa, New ZealandAugust 8, 1904 · 199 km S of this epicenter
- 6.856 km SSE of Castlepoint, New ZealandAugust 5, 1917 · 135 km SW of this epicenter
- 6.75 km SSW of Hastings, New ZealandJune 28, 1921 · 102 km NW of this epicenter
- 6.748 km ENE of Opotiki, New ZealandOctober 6, 1914 · 282 km N of this epicenter
- 6.4off the east coast of the North Island of New ZealandFebruary 8, 1931 · 83 km N of this epicenter
- 6.384 km SSE of Castlepoint, New ZealandSeptember 12, 1919 · 146 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 261 recorded deaths. The most severe:
- 1931M7.7
Hawke Bay
2 Feb 1931 · 146 km away · intensity IX
261 deaths$25 million damagetsunami
- 1855M8.0
Wellington,Waiouru,Wanganui,Otaki
23 Jan 1855 · 228 km away
Severe damage ($5–24M)tsunami
- 1848M7.9
N.
15 Oct 1848 · 269 km away
Limited damage (under $1M)tsunami
- 1843M7.5
Wanganui
8 Jul 1843 · 220 km away
tsunami
- 1904M7.5
E Of North Island
8 Aug 1904 · 42 km away
tsunami
- 1931M7.1
N
13 Feb 1931 · 113 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.