In the late afternoon of Saturday June 28th, 2025, a significant MAG-5.5 earthquake hit in the South Pacific Ocean 173 kilometer from Nuku‘alofa, Tonga. Roughly 90 thousand people may have felt this earthquake.
Felt the earthquake? Share this article: 
Earthquake Summary
This earthquake hit under water in the South Pacific Ocean, 162 kilometers (100 mi) off the coast of Tonga, 173 kilometer north-northwest of Nuku‘alofa in Tongatapu. The center of this earthquake had an intermediate depth of 229 km.
| Date and Time: | Jun 28, 2025 05:17PM (Tongatapu Time) - Jun 28, 2025 04:17 Universal Time. |
|---|---|
| Location: | 173 km NNW of Nuku‘alofa, Tongatapu, Tonga. Coordinates 19°49'48"S 176°5'25"W. |
| Map: |  Map of area around epicenter. Click to open in Google Maps. |
| Magnitude: | MAG 5.5 Detected by 33 stations. Maximum Error Range ±0.054 . |
| Depth: | 229 km (142 mi) An intermediate depth. |
| Max. Intensity: | III
Weak On the Modified Mercalli Scale. |
| Tsunami Risk: | Tsunami very unlikely Earthquakes under MAG-6.5 at depths deeper than 100km are very unlikely to cause tsunami's. Always stay cautious - More info here. |
Minimal impact predicted
Based on scientific estimates by the US Geographic Survey (USGS), the risk of high fatalities for this earthquake is classified at level GREEN (low). They expect an 65% likelyhood of between 0 and 1 fatalities, and a 96% chance that the number of fatalities falls no higher than 10.
The USGS classifies the economic impact of this earthquake at level GREEN (low). They expect an 65% likelyhood of between 0 and 1 million US Dollars in economic damage and impact, and a 96% chance that the economic impact of this earthquake falls no higher than 10 million USD.
Roughly 90 thousand people exposed to shaking
An estimated 90 thousand have been exposed to shaking (An MMI or Modified Mercalli Intensity level II or higher) as a result of this earthquake according scientific estimates published by the USGS.
The highest earthquake impact level for this earthquake is III, which corresponds with weak shaking and probably no damage. Roughly 75,810 people are expected to be exposed to this level.
People in 2 countries have been exposed to shaking. In Tonga , around 90 thousand people, with impact levels up to III (weak shaking, probably no damage).
| People | MMI Level | Shaking | Damage |
|---|---|---|---|
| 0 | I |
Not noticable | None |
| 14,000 | II |
Very weak | None |
| 75,810 | III |
Weak | Probably none |
| 0 | IV |
Light | Likely none |
| 0 | V |
Moderate | Very light |
| 0 | VI |
Strong | Light |
| 0 | VII |
Very Strong | Moderate |
| 0 | VIII |
Severe | Moderate to heavy |
| 0 | IX |
Violent | Heavy |
| 0 | X |
Extreme | Very heavy |
Nearby towns and cities
This earthquake may have been felt in Tonga . The closest significant population center near the earthquake is Nuku‘alofa in Tongatapu, Tonga. Nuku‘alofa is located 173 kilometer (107 mi) north-northwest of the epicenter. Nuku‘alofa experienced an earthquake intensity (MMI Scale) of roughly III. That level implies weak shaking and probably no damage.
Overview of nearby places
| Distance | Place | Intensity (MMI) |
|---|---|---|
| 173 km (107 mi) SSE from epicenter |
Nuku‘alofa Tongatapu, Tonga. |
III
Weak |
Earthquake Intensity Map
The graph below overlays a map of the region around the epicenter with earthquake intensity data provided by the US Geographic Survey. The highest intensity level detected for this earthquake is III.
Risk of aftershocks?
This earthquake did not have any significant foreshocks nor aftershocks occurring within 100km (62 mi) of its epicenter.
Aftershocks are usually at least 1 order of magnitude less strong than main shocks. The more time passes, the smaller the chance and likely strength of any potential aftershocks.
In only six percent of cases, significant earthquakes are followed by a larger main shock, making the current earthquake a foreshock. While the chance of this happening is not so large, it is adviced to maintain cautiousness in the hours and days following a major earthquake.
Read: How to Stay Safe during an Earthquake (cdc.gov).Earthquakes like this happen often in the region
Earthquakes of this strength are very common in the region. This is the strongest earthquake to hit since May 14th, 2025, when a 6.4 magnitude earthquake hit 147 km (92 mi) further north-northeast. An even stronger magnitude 8.2 earthquake struck on August 19th, 2018.
In total, 144 earthquakes with a magnitude of 5.5 or higher have been registered within 300km (186 mi) of this epicenter in the past 10 years. This comes down to an average of once every 25 days.
Tsunami very unlikely
For a serious tsunami to occur, earthquakes usually need to have a magnitude of at least 6.5 and occur at a shallow depth of maximum 100km. Neither are the case with this earthquake. However always stay cautious and monitor advice from local authorities.
Tsunami Risk Factors
| Factor | Under Sea? | MAG-6.5 or stronger? | Shallow depth? |
|---|---|---|---|
| Explanation | Almost all tsunami's are caused by earthquakes with their epicenter under sea or very near the sea. However stay cautious in coastal areas as earthquakes on land may cause landslides into sea, potentially still causing a local tsunami. | Under MAG 6.5: Very unlikely to cause a tsunami. MAG 6.5 to 7.5: Destructive tsunami's do occur, but are uncommon. Likely to observe small sea level changes. MAG 7.6+: Earthquakes with these magnitudes might produce destructive tsunami's. |
Most destructive tsunami's are caused by shallow earthquakes with a depth between 0 and 100km under the surface of the earth. Deeper tsunami's are unlikely to displace to ocean floor. |
| This Earthquake | This earthquake appears to have struck under the sea. | Not this earthquake. This earthquake had a magnitude of 5.5. Earthquakes of this strength are unlikely to trigger a tsunami. |
Not this earthquake. This earthquake occurred at a depth of 229 km (142 mi). Earthquakes this deep in the earth are unlikely to trigger a tsunami. |
Sources
Last updated 19/07/25 06:38 (). As more information on this earthquake becomes available this article will be updated. This article is automatically composed based on data originating from multiple sources.
- US Geographic Society (USGS): Earthquake us7000q99p
- European-Mediterranean Seismological Centre (EMSC): Earthquake 20250628_0000049
- Geonames.org: World Cities Database
- Google Maps: Static API
- Earthquakelist.org: Historic Earthquakes Database
Share this article:
