QuakeScout
Magnitude4.5

Reviewed by USGS8y ago

M4.5 earthquake in Fiji region

Tuesday, October 23, 2018, 17:13:19 UTC · 19.609°S, 177.733°W

A magnitude 4.5 earthquake struck in Fiji region on Tuesday, October 23, 2018, 17:13:19 UTC, at a depth of 529.9 km (deep). It is the strongest earthquake within 300 km since an M4.7 on October 21, 2018.

Magnitude
4.5
Light · mb
Depth
530 km
Deep
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

131 km

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

Depth: deep

530 km

Deep earthquakes (over 300 km) happen deep inside subducting plates. They rarely cause damage, but can be felt faintly over very large distances.

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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.5 on October 26, 2018. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M41h6h1d3d7d14d30dMainshock M4.5
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.3278 km WNW of Haveluloto, Tonga7y ago · 41 km SE of this epicenter
  2. 4.1295 km WNW of Haveluloto, Tonga8y ago · 28 km S of this epicenter
  3. 4.5298 km WNW of Haveluloto, Tonga8y ago · 42 km S of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 1,889 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.22018 Fiji EarthquakeAugust 19, 2018 · 172 km N of this epicenter
  2. 8.0TongaJanuary 4, 1903 · 289 km E of this epicenter
  3. 7.8159 km W of Pangai, TongaDecember 14, 1950 · 195 km E of this epicenter
  4. 7.8Fiji regionJanuary 1, 1919 · 49 km NW of this epicenter
  5. 7.8192 km WSW of Haveluloto, TongaOctober 14, 1997 · 295 km S of this epicenter
  6. 7.7Fiji regionAugust 19, 2002 · 297 km SW of this epicenter
  7. 7.6178 km E of Levuka, FijiFebruary 22, 1909 · 206 km NW of this epicenter
  8. 7.6240 km E of Levuka, FijiMarch 9, 1994 · 189 km N of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 11 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 2018M8.2

    Fiji Islands

    19 Aug 2018 · 172 km away · intensity V

    tsunami

  2. 1937M8.1

    Fiji Islands

    16 Apr 1937 · 224 km away

  3. 1903M8.0

    Tonga Islands

    4 Jan 1903 · 289 km away

  4. 1909M7.8

    Fiji Islands

    22 Feb 1909 · 223 km away

  5. 1919M7.8

    Fiji Islands

    1 Jan 1919 · 49 km away

    tsunami

  6. 1950M7.7

    Tonga Islands

    14 Dec 1950 · 182 km away · intensity VI

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

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