Abstract
Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small (<5 km3) flank collapse on a terrestrial volcano could immediately precede a devastating eruption. The lateral collapse of volcanic island flanks, such as in the Canary Islands, can be far larger (>300 km3), but can also occur in complex multiple stages. Here, we show that multistage retrogressive landslides on Tenerife triggered explosive caldera-forming eruptions, including the Diego Hernandez, Guajara and Ucanca caldera eruptions. Geochemical analyses were performed on volcanic glasses recovered from marine sedimentary deposits, called turbidites, associated with each individual stage of each multistage landslide. These analyses indicate only the lattermost stages of subaerial flank failure contain materials originating from respective coeval explosive eruption, suggesting that initial more voluminous submarine stages of multi-stage flank collapse induce these aforementioned explosive eruption. Furthermore, there are extended time lags identified between the individual stages of multi-stage collapse, and thus an extended time lag between the initial submarine stages of failure and the onset of subsequent explosive eruption. This time lag succeeding landslide-generated static decompression has implications for the response of magmatic systems to un-roofing and poses a significant implication for ocean island volcanism and civil emergency planning.
Highlights
Volcanic island landslides, their associated tsunamis, and volcanic eruptions pose significant natural hazards to both life and infrastructure
Direct observations of volcano flank collapse on land have shown that they can be immediately succeeded by major explosive eruptions
The resulting landslide was followed after thirty seconds by a devastating series of explosive eruptions including a lateral blast that took fifty-eight lives, cost over a billion US$ in damages, and resulted in unquantified potential respiratory health risks to local residents involved[15,16,18,19]
Summary
The sediment piston cores of this study form a component of previous published research and an established basin stratigraphy[7,8,65]. Volcanic glasses from the individual sub-units of the event beds was completed using the SwiftEd EDS as part of the Hitachi TM1000 SEM at BOSCORF and the methodology of Hunt et al.[38] (Supplementary 2). Samples were recovered from the El Abrigo and Granadilla ignimbrites on Tenerife and analysed using the SwiftEd EDS as part of the Hitachi TM1000 SEM at BOSCORF and the methodology of Hunt et al.[38] (Supplementary 3). These data were validated for accuracy and precision using a series of international standard reference materials (SRMs) as analytical glasses, produced using methodology of Hunt et al.[38] (Supplementary 4). Any addition data can be made available upon request of the lead author
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