Insights into the recurrent energetic eruptions that drive Awu, among the deadliest volcanoes on Earth

Abstract

Abstract. The little-known Awu volcano (Sangihe Islands, Indonesia) is among the deadliest, with a cumulative death toll of 11 048. In less than 4 centuries, 18 eruptions were recorded, including two VEI 4 and three VEI 3 eruptions with worldwide impacts. The regional geodynamic setting is controlled by a divergent-double-subduction collision and an arc–arc collision. In that context, the slab stalls in the mantle, undergoes an increase in temperature, and becomes prone to melting, a process that sustained the magmatic supply. Awu also has the particularity of hosting alternatively and simultaneously a lava dome and a crater lake throughout its activity. The lava dome passively erupted through the crater lake and induced strong water evaporation from the crater. A conduit plug associated with this dome emplacement subsequently channeled the gas emission to the crater wall. However, with the lava dome cooling, the high annual rainfall eventually reconstituted the crater lake and created a hazardous situation on Awu. Indeed with a new magma injection, rapid pressure buildup may pulverize the conduit plug and the lava dome, allowing lake water injection and subsequent explosive water–magma interaction. The past vigorous eruptions are likely induced by these phenomena, possible scenarios for future events.

Elevated CO2 Emissions during Magmatic-Hydrothermal Degassing at Awu Volcano, Sangihe Arc, Indonesia

“…In the time interval between the two gas surveys, Awu went through a VEI 2 eruption that ended with the formation of a lava dome [29,30]. This latter reached its current size in less than two weeks then it completely stopped growing and progressively cooled down until its 5.6 MW radiant flux in 2015 [24]. Such cooling has subsequently allowed the progressive development of a hydrothermal system highlighted by the 2015 gas results (Table 3).…”

“…Note that over its historical activity, the crater also hosted a crater lake. Rock samples collected since 1966 indicate a basaltic andesite magmatic source [22][23][24][25] with the phenocrysts composed mainly of plagioclase, olivine, orthopyroxene, and hornblende [25].…”

“…At the regional scale, two recorded tsunamis were triggered by the 1856 and 1892 eruptions [39,40]. These intense eruptive events have claimed a total of 11,048 victims on the island of Sangihe [24], mainly through lahars and pyroclastic flows [30,[41][42][43][44]. Awu is thus one of the deadliest volcanoes on Earth [24] (Bani et al, 2020).…”

Complex tsunami hazards in eastern Indonesia from seismic and non-seismic sources: Deterministic modelling based on historical and modern data

“…With the presence of more than 130 active volcanoes in Indonesia (Katili 1975;Lavigne et al 2008), this country is a hot spot for volcanic tsunamis. Awu volcano in Sulawesi, described in a recent study by Bani et al (2020) as "among the deadliest volcanoes on Earth", generated a tsunami in 1856, which also has not been studied in terms of tsunami hazard (Fig. 1).…”