An initial assessment of volcanic meteo-tsunami hazard in the South China Sea: what we learned and how to move forward

Volcanic meteo-tsunamis (VMTs), 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 explored such phenomena, none have investigated analogous scenarios in regions with potential occurrence of large undersea eruptions. We focus on areas along the South China Sea (SCS), which is a region among the most densely populated on Earth and historically prone to volcanic activity. We simulated VMTs from one intra-basin volcano (KW-23612) and three extra-basin volcanoes (Banua Wuhu, Kikai, and Fukutoku-Oka-no-Ba), to assess which countries around the SCS could be more exposed to such phenomena. Our results generally indicate that the SCS can be considered a low-hazard region from VMTs, and that the worst-case scenarios are produced by eruptions/tsunamis from within the SCS basin itself, with offshore waves up to 10 and 20 cm offshore Hong Kong and Manila respectively. Countries bordering the shallower Sunda Shelf (Malaysia, Thailand, Cambodia, and southern Vietnam), instead, receive much smaller waves (<2 cm). Despite the limitations, this study sets the basis to quantitatively assess hazard from volcanic meteo-tsunamis at key locations in the SCS.