QuakeScout
Magnitude4.6

Reviewed by USGS5y ago

M4.6 earthquake south of the Kermadec Islands

Saturday, April 3, 2021, 09:02:24 UTC · 32.728°S, 178.551°W

A magnitude 4.6 earthquake struck south of the Kermadec Islands on Saturday, April 3, 2021, 09:02:24 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M4.6 on March 31, 2021.

Magnitude
4.6
Light · mb
Depth
10 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

120 tons of TNT

That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.

Tectonic setting

79 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

10 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.6 on April 27, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M41h6h1d3d7d14d30dMainshock M4.6
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.5south of the Kermadec Islands5y ago · 37 km NE of this epicenter
  2. 4.6south of the Kermadec Islands5y ago · 33 km W of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 1,784 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 · 247 km NE of this epicenter
  2. 7.4south of the Kermadec IslandsJune 18, 2020 · 90 km SE of this epicenter
  3. 7.4Kermadec Islands regionMay 16, 2006 · 124 km NW of this epicenter
  4. 7.3Kermadec Islands, New ZealandJuly 25, 1968 · 218 km N of this epicenter
  5. 7.3Kermadec Islands, New ZealandJune 15, 2019 · 236 km N of this epicenter
  6. 7.2Kermadec Islands, New ZealandFebruary 9, 1978 · 254 km NE of this epicenter
  7. 7.2Kermadec Islands, New ZealandApril 17, 1919 · 245 km N of this epicenter
  8. 7.1Kermadec Islands, New ZealandJune 29, 1910 · 245 km NE of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 1968M7.3

    S Of, Raoul

    25 Jul 1968 · 215 km away

    Limited damage (under $1M)tsunami

  2. 1978M7.7

    S Of

    9 Feb 1978 · 254 km away

  3. 2020M7.4

    S Of, Raoul

    18 Jun 2020 · 90 km away · intensity VII

    tsunami

  4. 2019M7.2

    S Of, Raoul

    15 Jun 2019 · 218 km away

    tsunami

  5. 2013M6.5

    S Of, Raoul

    30 Sep 2013 · 202 km away

    tsunami

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

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