M7.4 earthquake 47 km WSW of Hastings, New Zealand

Monday, February 2, 1931, 22:46:52 UTC · 39.741°S, 176.316°E

A magnitude 7.4 earthquake struck 47 km WSW of Hastings, New Zealand on Monday, February 2, 1931, 22:46:52 UTC, at a depth of 35.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.

Magnitude: 7.4; Major · mw
Depth: 35 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

1.9 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

33 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

35 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 M7.3 on February 13, 1931. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 9 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

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 265 recorded deaths. The most severe:

1931M7.7
Hawke Bay
2 Feb 1931 · 25 km away · intensity IX
261 deaths$25 million damagetsunami
1848M6.0
Awatere River, Marlborough
18 Oct 1848 · 290 km away
3 deathstsunami
1914
North Island
6 Oct 1914 · 271 km away · intensity VIII
1 deathModerate damage ($1–5M)tsunami
1855M8.0
Wellington,Waiouru,Wanganui,Otaki
23 Jan 1855 · 201 km away
Severe damage ($5–24M)tsunami
1848M7.9
N.
15 Oct 1848 · 232 km away
Limited damage (under $1M)tsunami
1868M7.6
Tasman Sea
18 Oct 1868 · 287 km away
tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers