QuakeScout
Magnitude4.3

Reviewed by USGSTonga49y ago

M4.3 earthquake 199 km SW of Vaini, Tonga

Friday, July 8, 1977, 09:27:56 UTC · 22.330°S, 176.673°W

A magnitude 4.3 earthquake struck 199 km SW of Vaini, Tonga on Friday, July 8, 1977, 09:27:56 UTC, at a depth of 269.0 km (intermediate).

Magnitude
4.3
Light · mb
Depth
269 km
Intermediate
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

43 tons of TNT

That is about 1/354 of the Hiroshima bomb. A magnitude 5.0 releases about 11 times more energy.

Tectonic setting

2 km

from the nearest mapped plate boundary, between the Tonga and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: intermediate

269 km

Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.

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 M4.9 on July 15, 1977. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M4.3
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.9154 km SW of Haveluloto, Tonga49y ago · 45 km NE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 326 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.6south of the Fiji IslandsDecember 18, 1963 · 270 km S of this epicenter
  2. 7.5262 km WNW of Haveluloto, TongaMay 21, 1962 · 262 km N of this epicenter
  3. 7.4Fiji regionSeptember 28, 1957 · 264 km NW of this epicenter
  4. 7.3227 km WNW of Haveluloto, TongaApril 16, 1937 · 204 km N of this epicenter
  5. 7.3Fiji regionMay 25, 1944 · 297 km W of this epicenter
  6. 7.2Fiji regionOctober 9, 1967 · 289 km NW of this epicenter
  7. 7.2241 km WNW of Houma, TongaAugust 21, 1911 · 266 km N of this epicenter
  8. 7.2280 km WNW of Houma, TongaDecember 14, 1910 · 252 km NW of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1 recorded deaths. The most severe:

  1. 1977M7.2

    Tonga Trench

    22 Jun 1977 · 100 km away · intensity IV

    1 death$1 million damagetsunami

  2. 1937M8.1

    Fiji Islands

    16 Apr 1937 · 98 km away

  3. 1957M7.5

    Fiji Islands

    28 Sep 1957 · 286 km away

  4. 1963M7.5

    Tonga Trench

    18 Dec 1963 · 275 km away

    tsunami

  5. 1853

    Tonga Trench

    24 Dec 1853 · 202 km away

    tsunami

  6. 1907

    S Of Tonga

    1907 · 162 km away

    tsunami

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

Nearby trackers

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