Volcanic meteo-tsunamis, though rare, can pose significant threats to people, as exemplified by the 2022 Hunga Tonga – Hunga Ha’apai (HT-HH) eruption in the SW Pacific. While various studies have delved into the complexities of such phenomena, none have explored analogous scenarios in regions with potential occurrence of large eruptions near or under the sea. We focus on coastal areas along the South China Sea (SCS), among the most densely populated on Earth and historically prone to volcanic activity, including the catastrophic 1883 Krakatau eruption. Here we strategically chose one intra-basin volcano, KW-23612 in the northern SCS, and three extra-basin volcanoes, Banua Wuhu in the Celebes Sea, and Kikai and Fukutoku-Oka-no-Ba in the northern Philippines Sea (southern Japan), from which we simulated volcanic meteo-tsunamis with scaled intensities of the HT-HH event, to assess which countries around the SCS could be more at risk from the occurrence of such phenomena. Our results show that the worst-case scenarios are produced by eruption/tsunamis from the northern SCS, producing offshore waves up to 10 cm offshore Macau and Hong Kong, and up to 20 cm offshore Manila. In contrast, countries bordering the shallow Sunda Shelf (Malaysia, Thailand, Cambodia, and southern Vietnam) seem less at risk from volcanic meteo-tsunamis, though we observed some amplification effects along the deeper Singapore Strait. This study is the first of its kind in the region and sets the basis to investigate amplification effects, and shallow coastal dynamics at key locations, after integrating higher resolution bathymetry data.

South-east Asia is one of the most volcanically active places on Earth, with the majority of the volcanoes located in Indonesia and in the Philippines. Indochina (Myanmar, Cambodia, Laos, Thailand and Vietnam) also hosts a certain number of volcanoes that for several reasons (post-World War II conflicts, little accessibility due to dense vegetation, no significant historical activity recorded), have been little studied so far. Some of these volcanoes show evidence of recent (Quaternary) activity, therefore, a systematic assessment of the threat these volcanoes may pose to resident populations is needed in the region. A recent study on the inferred location of the Australasian meteorite impact (the largest known young meteorite on Earth) provided an unprecedented amount of data for the Bolaven Volcanic Field in Laos, in terms of geological mapping, location of vents, and over 30 absolute ages of lava flows and vents. On this basis, besides additional data obtained for this work, we used the Bolaven Volcanic Field as a case study, to assess the potential exposure of populations and infrastructure to lava flows in case of an eruption in the field. Key results suggest that an overall area of ~5500 km2 is potentially exposed to lava flows in case of eruption, including over 2000 km of roads, 400 km of power lines, two power stations and two dams, and over 500 km2 of agricultural lands, with the potential to affect about 300,000 people living in this area, and their main businesses (hydropower and coffee production). In addition, the abundance of water in this region may lead to life-threatening explosions from phreatomagmatic eruptions. Finally, based on the data available we provide a maximum estimate of the past eruption frequency of the field, which is approximately 10,400 years. Our study provides a number of techniques and approaches (remote sensing of potential sources and past flows, lava flow simulations and open-access exposure data) that can be used to assess hazards and exposure at other understudied volcanoes.