Geodiversity and Its Implication for Geoconservation of the Youngest Eruptive Sites of Western Samoa

Abstract

Western Samoa experienced its latest volcanic eruption between 1905 and 1911 that produced a complex scoria and lava spatter cone and an extensive lava field that destroyed Sale'aula village near the Pacific coast. This eruption referred to as the Matavanu eruption and it provided pāhoehoe type lava flows with superbly preserved surface textures, tumuli, and some littoral explosion craters in its distal lava field. The unique nature of the location made it to be selected as one of the "The First 100 IUGS Geological Heritage Sites" in October 2022. The region has been under investigation to document the geoheritage elements of the location, estimate its geodiversity and explore the potential to develop a geopark together with local communities. All this work intends to provide a firm knowledge base to identify effective geoconservation strategies. While the youngest eruptive products after over 100 years of revegetation are restricted in a coastal zone, previous research demonstrated that other young volcanic eruptions also took place in northern Savai'i in 1760 and 1902. Here we provide further data based on systematic evaluation of SENTINEL satellite imagery in combination with ALOS-PALSAR and SRTM 30-m resolution digital terrain modelbased calculation of morphometric elements to demonstrate the young volcanic landscape in northern Savai'i has great volcanic geodiversity and the entire region should be considered under specific geoconservation strategies. The young volcanic landforms of scoria cones in the high-altitude regions of the island alongside with extensive and commonly tube-fed lava flows invaded the northern region of Savai'i also pose volcanic hazard to the region hence volcanic geoheritage can be the core element to enforce strong community volcanic hazard resilience. The newly proposed Samoa Geopark Project is the perfect avenue to achieve this.