Samoa & Tonga 

On 20 December 2021, the Hunga Tonga-Hunga Ha'apai volcano (named after the two surrounding islets, one closer to the island of Tongatapu and the other closer to the Ha'apai group of islands) erupted. The inhabitants of the main island of the Kingdom of Tonga, Tongatapu, and of the capital Nuku'alofa, although located around 65 kilometres to the south-east, quickly noticed that the volcano had reawakened. An eruptive column rose above the craters, generously fed by the Pacific Ocean, which vaporised with the heat. Over the following weeks, the density of the cloud led to the formation of volcanic lightnings, flashes of light contrasting with the surrounding darkness. On 14 January 2022, the activity seemed to have died down, leading some researchers to postulate the end of the eruption. However, the truce proved to be short-lived, and a powerful explosion on 14 January created a small tsunami, reported by several Tongatapu residents. The following day, 15 January 2022, the eruption reached its paroxysm. The explosion generated an impressive eruptive column, reaching an altitude of nearly 60 kilometres in the mesosphere. Once again, a tsunami warning was triggered. Despite the widespread absence of sirens, the shockwave and initial detonation were enough to alert the population, who quickly gathered in the interior of the island, seeking to reach the few 'high' points of Tongatapu. Tongans are used to earthquakes and tsunami warnings, but in this case, the absence of a tremor took them by surprise, as they were not expecting a volcano to unleash a destructive wave.

At the time of our visit, in April-May 2025, the traces of the Tsunami are still clearly visible. On the west coast of Tongatapu, where the island's longest and most beautiful sandy beaches can be found, decrepit signs announce resorts that today consist of nothing more than concrete foundations. The buildings, although protected by breakwaters, have been flattened by the waves. As Tevita, our guide for the day, explains, the tsunami was the last straw for the owners of these establishments: the COVID crisis and two hurricanes had already taken their toll, and after the events of January 2022, they decided not to rebuild. Three years on, the vegetation has grown back: "that's because the ash from the volcano was not acidic. On the contrary, everything is growing better now", Tevita explains. To test the quality of the ash, the people we spoke to didn't need any precision instruments. Our guide's niece, Losalio, told us that people from the volcanic island of Niuaofo'ou, in the very north of the archipelago, used to taste the ash to determine its composition: if it tasted salty, it meant "bad" ash. If the taste was more neutral, the ash was 'good', containing nutritious minerals for the plantations.

In Tongatapu, tsunamis are not exceptional events. We also had the opportunity to visit Maka Tolo 'a Maui, also known as Tsunami Rock, a coral rock measuring 780m3 and weighing more than 1600 tons, which seems to have been deposited more than a hundred metres from the coast. Legend has it, as our guide explains, that the rock was thrown by the god Maui to silence a noisy rooster. But legend aside, this piece of reef is considered to be the largest erratic rock in the world, plucked from the waves by a tsunami of immense proportions around the 15th century.

Despite the many traces and memories of telluric activity, the island of Tongatapu is not of volcanic origin, unlike the islands of the Samoan archipelago. Located to the north of Tonga, the archipelago's two main islands - Upolu, the capital, and Savai'i, which is larger and less populated - were formed by the gradual accumulation of lava flows with a very smooth, liquid consistency, which enabled them to spread rapidly and far from the craters. Upolu and Savai'i have the characteristic relief of shield volcanoes, with fairly gentle slopes and a broad base. At Upolu, there are no visible signs of volcanic activity today, as the last eruption probably predates human occupation. At Savai'i, on the other hand, the last eruption was much more recent. It took place between 1905 and 1911, and spread from the crater of Mt. Matavanu in the north of the island. It engulfed the villages of Sale'aula and Salago. Today, the lava field is still clearly visible, showing the bulges created by this fluid lava. On the site, which has become a modest tourist attraction, you can see a church, said to have been "saved" from the lava, and the "virgin's grave", the spared tomb of the village chief's daughter, who had died shortly before. On site, our guide also took us to the lava caves that form long tunnels, home to small birds called peka-peka. These birds sleep during the day and come out at night, and are locally compared to peka, the flying fox.

As we circumnavigated the island by road, we noticed an intriguing phenomenon, for which we received no precise explanation: in front of many houses, large blocks of lava have been placed, making access to the buildings difficult. One hypothesis put forward to us is purely aesthetic; the gardens are generally all decorated and very well maintained in the hope of winning the annual competition for the most beautiful village, and the lava rock - our guide tells us - is considered visually attractive. However, when we take a look at the colourful flower gardens, covering the ground with black rock seems counter-intuitive. Another possible explanation is that the rocks are used to dry the pandanus leaves, which are then woven to create various objects.

In Upolu, as in Savai'i, a recurrent use of volcanic rocks is to cover the tombs of chiefs, forming a pile that will be larger, we are told, if the chief was important. In Tongatapu, a partially comparable phenomenon is observed: without making such imposing tombs, it is regular for them to be covered with volcanic rocks, also considered aesthetically pleasing (and contrasting with the whiteness of the island's rock and limestone sand).

The two nations, linked by many myths and perceived locally as culturally close, have a wide variety of views of earth and volcanic phenomena, reflecting the diversity of soils and phenomena experienced. The region is rich in volcanic stories in the plural, and it would be fascinating to explore them further.