QuakeScout
Magnitude4.5

Reviewed by USGS5y ago

M4.5 earthquake southeast of the Loyalty Islands

Monday, March 15, 2021, 05:50:34 UTC · 22.699°S, 172.851°E

A magnitude 4.5 earthquake struck southeast of the Loyalty Islands on Monday, March 15, 2021, 05:50:34 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M4.7 on March 15, 2021.

Magnitude
4.5
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

85 tons of TNT

That is about 1/178 of the Hiroshima bomb. A magnitude 5.0 releases about 6 times more energy.

Tectonic setting

37 km

from the nearest mapped plate boundary, between the New Hebrides and Australian 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.7 on April 2, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M4.5
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.7southeast of the Loyalty Islands5y ago · 15 km NE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 814 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.7southeast of the Loyalty IslandsFebruary 10, 2021 · 128 km W of this epicenter
  2. 7.6south of the Fiji IslandsMarch 3, 1990 · 246 km E of this epicenter
  3. 7.6274 km ESE of Tadine, New CaledoniaMarch 16, 1928 · 255 km W of this epicenter
  4. 7.5southeast of the Loyalty IslandsJanuary 4, 1998 · 204 km W of this epicenter
  5. 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 128 km W of this epicenter
  6. 7.2southeast of the Loyalty IslandsAugust 12, 2016 · 37 km NE of this epicenter
  7. 7.1southeast of the Loyalty IslandsAugust 17, 1935 · 149 km W of this epicenter
  8. 7.1southeast of the Loyalty IslandsApril 14, 1906 · 163 km W 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. 2021M7.7

    Loyalty Islands

    10 Feb 2021 · 134 km away · intensity VII

    tsunami

  2. 1990M7.6

    Fiji Islands

    3 Mar 1990 · 246 km away

  3. 1928M7.5

    Loyalty Islands

    16 Mar 1928 · 254 km away

  4. 1943M7.5

    Loyalty Islands

    14 Sep 1943 · 206 km away

  5. 1944M7.5

    Loyalty Islands

    5 Oct 1944 · 90 km away

  6. 2016M7.2

    Loyalty Islands

    12 Aug 2016 · 37 km away · intensity VI

    tsunami

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

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