An initial assessment of volcanic meteo-tsunamis hazard in the South
China Sea shows considerable bathymetric effects
Abstract
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.