Reviewed by USGSNew Zealand97y ago
M7.3 earthquake 40 km E of Waiouru, New Zealand
Friday, February 13, 1931, 01:27:26 UTC · 39.421°S, 176.129°E
A magnitude 7.3 earthquake struck 40 km E of Waiouru, New Zealand on Friday, February 13, 1931, 01:27:26 UTC, at a depth of 45.0 km (shallow). It is the strongest earthquake within 300 km since an M7.4 on February 2, 1931.
- Magnitude
- 7.3
- Major · mw
- Depth
- 45 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VII
- Very strong (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
1.3 megatons of TNT
That is about 89 times the Hiroshima bomb. It released about 2,818 times the energy of a magnitude 5.0.
Tectonic setting
32 km
from the nearest mapped plate boundary, between the Kermadec and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
45 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 1 M2.5+ earthquake within 200 km in the following 30 days; the largest was M6.2 on March 8, 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 12 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 · 39 km SE of this epicenter
- 7.044 km N of Whakatane, New ZealandNovember 22, 1914 · 217 km N of this epicenter
- 6.856 km SSE of Castlepoint, New ZealandAugust 5, 1917 · 219 km S of this epicenter
- 6.75 km SSW of Hastings, New ZealandJune 28, 1921 · 67 km SE of this epicenter
- 6.748 km ENE of Opotiki, New ZealandOctober 6, 1914 · 222 km NE of this epicenter
- 6.4off the east coast of the North Island of New ZealandFebruary 8, 1931 · 107 km E of this epicenter
- 6.384 km SSE of Castlepoint, New ZealandSeptember 12, 1919 · 245 km S of this epicenter
- 6.350 km ESE of Castlepoint, New ZealandFebruary 12, 1930 · 193 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 262 recorded deaths. The most severe:
- 1931M7.7
Hawke Bay
2 Feb 1931 · 40 km away · intensity IX
261 deaths$25 million damagetsunami
- 1914
North Island
6 Oct 1914 · 255 km away · intensity VIII
1 deathModerate damage ($1–5M)tsunami
- 1855M8.0
Wellington,Waiouru,Wanganui,Otaki
23 Jan 1855 · 225 km away
Severe damage ($5–24M)tsunami
- 1848M7.9
N.
15 Oct 1848 · 250 km away
Limited damage (under $1M)tsunami
- 1868M7.6
Tasman Sea
18 Oct 1868 · 281 km away
tsunami
- 1843M7.5
Wanganui
8 Jul 1843 · 110 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.