M5.5 Earthquake near Houma, Tonga — 28 June 2025

Moderate earthquakes can damage poorly built or unreinforced structures near the epicentre, while well-engineered buildings typically escape serious harm. Shaking is often strong enough to wake sleeping residents over a wide area.

A magnitude 5.5 earthquake radiates roughly 2,682 tons of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 465, which is below the USGS threshold of more than 600 for its significant-earthquake list. The ranking combines magnitude with available Did You Feel It responses and PAGER alert level; it is not a direct measurement of damage.

What the magnitude scale actually measures →

The epicentre was located at -19.8595, -176.0640 — 165 km north-northwest of Houma. The closest other recorded event was a magnitude 4.7 earthquake 43 km south-southeast of here on 03 January 2026.

At 238 km this was an intermediate-depth earthquake. Energy from events at this depth spreads out before it reaches the surface, which usually means weaker shaking near the epicentre than a shallow quake of the same magnitude, but shaking felt across a wider area.

This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size can be felt widely and may cause minor local damage. Its intermediate depth normally reduces peak shaking near the epicentre compared with a shallow event of the same magnitude.

Read more on how focal depth changes what you feel →

The USGS record does not carry a link to NOAA tsunami information. That field is not an all-clear and does not state whether a tsunami occurred. In this case, a damaging tsunami would be less likely because at M5.5 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; its 238 km focal depth is too great to deform the sea floor significantly; it occurred inland rather than beneath the sea floor. For an active coastal alert, use tsunami.gov or your local warning authority.

How earthquakes generate tsunamis, and what the alert levels mean →

No further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event.

206 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 7.5 event near Neiafu on 24 March 2026. This M5.5 event released about 1,000 times less energy than that event.

How long aftershock sequences last, and how large they get →

This earthquake is part of the June 2025 worldwide record. Browse the full monthly archive to compare periods.