QuakeScout
Magnitude4.1

Reviewed by USGSNew Zealand51y ago

M4.1 earthquake in Kermadec Islands, New Zealand

Sunday, May 23, 1976, 13:58:54 UTC · 30.185°S, 177.704°W

A magnitude 4.1 earthquake struck in Kermadec Islands, New Zealand on Sunday, May 23, 1976, 13:58:54 UTC, at a depth of 33.0 km (shallow).

Magnitude
4.1
Light · mb
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: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

21 tons of TNT

That is about 1/707 of the Hiroshima bomb. A magnitude 5.0 releases about 22 times more energy.

Tectonic setting

110 km

from the nearest mapped plate boundary, between the Kermadec and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

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 50 km

USGS lists 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.7 on May 31, 1976. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M4.1
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.7Kermadec Islands, New Zealand51y ago · 32 km NW of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 371 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.21917 Kermadec Islands, New Zealand EarthquakeMay 1, 1917 · 151 km SE of this epicenter
  2. 8.01976 Kermadec Islands, New Zealand EarthquakeJanuary 14, 1976 · 196 km N of this epicenter
  3. 7.5Kermadec Islands regionFebruary 27, 1955 · 290 km NE of this epicenter
  4. 7.5Kermadec Islands, New ZealandNovember 16, 1917 · 40 km N of this epicenter
  5. 7.3Kermadec Islands regionSeptember 14, 1959 · 157 km N of this epicenter
  6. 7.3Kermadec Islands, New ZealandMarch 26, 1963 · 22 km N of this epicenter
  7. 7.3Kermadec Islands, New ZealandJuly 25, 1968 · 80 km SW of this epicenter
  8. 7.2Kermadec Islands regionJuly 2, 1974 · 209 km NE of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 8 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 1976M7.9

    Kermadec Islands

    14 Jan 1976 · 113 km away

    Limited damage (under $1M)tsunami

  2. 1968M7.3

    S Of, Raoul

    25 Jul 1968 · 96 km away

    Limited damage (under $1M)tsunami

  3. 1917M8.0

    Kermadec Islands

    1 May 1917 · 129 km away

    tsunami

  4. 1976M7.8

    Kermadec Islands

    14 Jan 1976 · 55 km away · intensity VIII

  5. 1959M7.7

    Kermadec Islands

    14 Sep 1959 · 199 km away

  6. 1943M7.6

    S Of

    14 Sep 1943 · 71 km away

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

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