QuakeScout
Magnitude7.6

Reviewed by USGSTonga3y ago

M7.6 earthquake 82 km WNW of Hihifo, Tonga

Wednesday, May 10, 2023, 16:02:00 UTC · 15.628°S, 174.493°W

A magnitude 7.6 earthquake struck 82 km WNW of Hihifo, Tonga on Wednesday, May 10, 2023, 16:02:00 UTC, at a depth of 210.0 km (intermediate). USGS received 26 “Did You Feel It?” reports, with a maximum reported intensity of VIII (severe). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M8.1 on September 29, 2009.

Tsunami flagUSGS sets this flag for large events in oceanic regions so tsunami warning centers review them. It does not by itself mean a tsunami occurred. Check tsunami.gov and local authorities for official messages.

Magnitude
7.6
Major · mww
Depth
210 km
Intermediate
Felt reports
26
Max intensity VIII
Est. shaking
VI
Strong (ShakeMap)
PAGER alert
Green
Impact estimate
Tsunami
Flag
Check tsunami.gov

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

3.8 megatons of TNT

That is about 252 times the Hiroshima bomb. It released about 7,943 times the energy of a magnitude 5.0.

Tectonic setting

31 km

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

Depth: intermediate

210 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

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

PlaceIntensityReportsDistance
96799<br>0.269IV · Light8481 km
Apia, Apia Urban Area, SamoaIV · Light6412 km
Neiafu, Vavaʿu, TongaVII · Very strong2397 km
Talimatau, North West Upolu, SamoaIV · Light2410 km
Leulumoega, North West Upolu, SamoaIV · Light1399 km
Makefu, _no region, NiueIII · Weak1646 km
Satalo, Rest of Upolu, SamoaIII · Weak1417 km
Toi, _no region, NiueIII · Weak1650 km
Hakupu, _no region, NiueIII · Weak1660 km
Tamakautoga, _no region, NiueIII · Weak1652 km
I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

Modelled from the ShakeMap and population data. Alert level green: low likelihood of casualties and damage.

V · Moderate shaking
4,400 people
IV · Light shaking
278,000 people

Estimated shaking in nearby towns

  • HihifocapitalPopulation 815VI · Strong
  • GataivaiPopulation 1,100IV · Light
  • AsaucapitalPopulation 6,600IV · Light
  • VailoacapitalPopulation 769IV · Light
  • Mata-UtucapitalPopulation 1,200IV · Light
  • LeulumoegacapitalPopulation 1,500IV · Light
  • MulifanuacapitalPopulation 4,500IV · Light
  • NeiafucapitalPopulation 4,300IV · Light

After the main event

Aftershocks within 200 km

USGS lists 32 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.3 on June 4, 2023. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M5M6M71h6h1d3d7d14d30dMainshock M7.6
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.173 km WNW of Hihifo, Tonga3y ago · 10 km SE of this epicenter
  2. 4.799 km NNE of Hihifo, Tonga3y ago · 120 km NE of this epicenter
  3. 5.3105 km NE of Hihifo, Tonga3y ago · 148 km E of this epicenter
  4. 4.293 km WSW of Hihifo, Tonga3y ago · 86 km S of this epicenter
  5. 4.387 km WNW of Hihifo, Tonga3y ago · 12 km N of this epicenter
  6. 4.083 km WNW of Hihifo, Tonga3y ago · 4 km SW of this epicenter
  7. 4.3102 km NE of Hihifo, Tonga3y ago · 142 km E of this epicenter
  8. 4.3106 km NNE of Hihifo, Tonga3y ago · 130 km NE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 1,972 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.12009 Samoa EarthquakeSeptember 29, 2009 · 257 km E of this epicenter
  2. 8.0The 1917 Samoa-Tonga EarthquakeJune 26, 1917 · 149 km NE of this epicenter
  3. 7.8146 km ESE of Hihifo, TongaDecember 26, 1975 · 228 km E of this epicenter
  4. 7.7133 km NE of Hihifo, TongaSeptember 1, 1981 · 168 km NE of this epicenter
  5. 7.6199 km ESE of Hihifo, TongaApril 2, 1977 · 282 km SE of this epicenter
  6. 7.488 km NNE of Hihifo, TongaApril 7, 1995 · 114 km NE of this epicenter
  7. 7.2117 km SSW of Hihifo, TongaJanuary 8, 2000 · 147 km S of this epicenter
  8. 7.219 km ENE of Hihifo, TongaOctober 15, 1984 · 95 km E 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, which together caused about 194 recorded deaths. The most severe:

  1. 2009M8.1

    Samoa Islands

    29 Sep 2009 · 257 km away

    192 deaths$285 million damagetsunami

  2. 1917M8.3

    Samoa Islands

    26 Jun 1917 · 161 km away

    2 deathsModerate damage ($1–5M)tsunami

  3. 1981M7.7

    Apia; American Samoa: Pago Pago

    1 Sep 1981 · 168 km away · intensity VI

    Limited damage (under $1M)tsunami

  4. 1977M7.6

    Apia

    2 Apr 1977 · 282 km away · intensity VI

    Limited damage (under $1M)tsunami

  5. 1975M7.8

    Samoa Islands

    26 Dec 1975 · 228 km away · intensity V

    tsunami

  6. 2023M7.6

    Hihifo

    10 May 2023 · 13 km away

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

Nearby trackers

Closest city pages