A magnitude 5.28 earthquake centred close to Tongatapu was felt in Nuku'alofa at 4:09 pm this afternoon, with a sharp upward jolt followed by a brief tremor.

The Geological Unit at Tonga's Ministry of Land and Survey made a preliminary recording of the epicenter located at 21.07°S, 174.82°W, at a depth of 130.8 km, at 13:09 UTC (4:09 pm local time).

Apai Moala, senior geological assistant, said they recorded the magnitude of the earthquake at 5.28 on the Richter scale.

"It was on the Indo-Australian plate, roughly in Eastern Tonga about 23km from Niutoua," he said, adding that the exact location needed to be verified with other readings from the wider region.

There was no tsunami alert after the earthquake. Apai said alerts were more likely to occur following earthquakes of 6.9 or greater magnitude, depending on their depth and location. A shallow earthquake was more likely to generate a tsunami than a very deep one.

"Nuku'alofa is the hub for our network of remote sites so we can follow every event closely," he said. "If a tsunami is generated we will put out a full alert."