QuakeScout
Magnitude4.0

Reviewed by USGSFiji21y ago

M4.0 earthquake 202 km ESE of Labasa, Fiji

Thursday, July 21, 2005, 22:31:29 UTC · 17.283°S, 178.953°W

A magnitude 4.0 earthquake struck 202 km ESE of Labasa, Fiji on Thursday, July 21, 2005, 22:31:29 UTC, at a depth of 521.8 km (deep).

Magnitude
4.0
Light · mb
Depth
522 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

15 tons of TNT

That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.

Tectonic setting

182 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

522 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 M4.6 on August 9, 2005. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M41h6h1d3d7d14d30dMainshock M4.0
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.6204 km ESE of Labasa, Fiji21y ago · 12 km NE of this epicenter
  2. 4.5201 km ESE of Labasa, Fiji21y ago · 25 km N of this epicenter
  3. 4.4205 km ENE of Levuka, Fiji21y ago · 37 km SE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 834 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.8Fiji regionJanuary 1, 1919 · 244 km S of this epicenter
  2. 7.6178 km E of Levuka, FijiFebruary 22, 1909 · 101 km S of this epicenter
  3. 7.6144 km SSW of Leava, Wallis and FutunaMay 23, 1956 · 206 km N of this epicenter
  4. 7.6240 km E of Levuka, FijiMarch 9, 1994 · 102 km SE of this epicenter
  5. 7.4227 km E of Levuka, FijiAugust 21, 1910 · 73 km SE of this epicenter
  6. 7.2Fiji regionMarch 31, 1907 · 230 km SE of this epicenter
  7. 7.2178 km ENE of Levuka, FijiMarch 29, 1998 · 33 km SW of this epicenter
  8. 7.1217 km E of Levuka, FijiJuly 8, 1916 · 90 km S of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 1919M6.9

    Rabi,Tunuloa Mission,Suvasavu

    3 Oct 1919 · 149 km away · intensity VIII

    Moderate damage ($1–5M)

  2. 1979M6.9

    Fiji Islands

    16 Nov 1979 · 124 km away

    Moderate damage ($1–5M)tsunami

  3. 1932M6.4

    Koro,Mudu,Suvasavu

    8 Mar 1932 · 171 km away · intensity VII

    Moderate damage ($1–5M)

  4. 1884

    Macuata

    Jan 1884 · 261 km away · intensity VII

    Limited damage (under $1M)tsunami

  5. 1909M7.8

    Fiji Islands

    22 Feb 1909 · 80 km away

  6. 1919M7.8

    Fiji Islands

    1 Jan 1919 · 244 km away

    tsunami

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

Nearby trackers

Closest city pages