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.
Highlights
Awu is a little-known active volcano located on the Sangihe arc, northeast of Indonesia
Trace elements normalized to N-MORB point to elevated ratios of large ion lithophile elements (LILEs), light rare-earth elements (LREEs), and high-field-strength elements (HFSEs) (Table 2, Fig. 3)
As emphasized in this work, the regular magma supply that sustained the activity of Awu is possibly linked to the peculiar geodynamic context of the region, controlled by the divergent double subduction and the subsequent arc– arc collision
Summary
Awu is a little-known active volcano located on the Sangihe arc, northeast of Indonesia. Since 1640, Awu went through 18 eruptions, including two of VEI 4 (volcanic explosivity index; Newhall and Self, 1982), in 1812 and 1966. In the database of volcanic eruption victims compiled by Tanguy et al (1998), Awu eruptions claimed a total of 5301 victims, including 963 casualties during the 1812 eruption, 2806 during the 1856 eruption, and 1532 during the 1892 eruption. This latter database did not take into account the 2508 victims of the 1711 eruption (Van Padan, 1983; Data Dasar Gunung Api, 2011) and 3200 deaths following the 1822 eruption (Lagmay et al, 2007). In this work we aim to highlight the intense eruptive character of Awu volcano and provide insights into the possible mechanisms that fueled the deadly energetic eruptions
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