M5.5 earthquake – Tonga

An earthquake measuring M5.5 was recorded at 04:17 UTC on June 28, 2025, approximately 165 km (102 miles) north-northwest of Houma, Tonga. The event occurred at a depth of 237.5 km (147.6 miles), based on data provided by the USGS.

The earthquake’s epicenter was located at coordinates 19.9°S, 176.1°W, placing it within the Tongan region of the southwest Pacific Ocean. The surrounding area features both scattered islands and deep oceanic trenches, with Houma being one of the closest significant localities.

Given the geography of this region, critical infrastructure near the epicenter may include local seaports, coastal airstrips, and communications facilities associated with island communities. Larger energy and transportation networks are typically few due to the remote and dispersed nature of Tonga’s islands.

There is no tsunami threat associated with this earthquake, based on its location and available data.

The significance index is 465 (on a scale that runs through 1 000), based on magnitude, felt reports, and estimated impact.

Tonga lies along the highly active Tonga-Kermadec subduction zone, where the Pacific Plate is subducting beneath the Indo-Australian Plate. This region is notable for frequent seismic activity, including intermediate and deep-focus earthquakes.

This information was last updated at 04:36 UTC on June 28, 2025.

Source: https://earthquake.usgs.gov/earthquakes/eventpage/us7000q99p