Contrasting catastrophic eruptions predicted by different intrusion and collapse scenarios

M Rincón,J L Granja-Bruña,A Márquez,B Van Wyk De Vries,R Herrera,A Alonso-Torres

doi:10.1038/s41598-018-24623-5

M Rincón, J L Granja-Bruña + Show 4 more

Open Access

https://doi.org/10.1038/s41598-018-24623-5

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Abstract

Catastrophic volcanic eruptions triggered by landslide collapses can jet upwards or blast sideways. Magma intrusion is related to both landslide-triggered eruptive scenarios (lateral or vertical), but it is not clear how such different responses are produced, nor if any precursor can be used for forecasting them. We approach this problem with physical analogue modelling enhanced with X-ray Multiple Detector Computed Tomography scanning, used to track evolution of internal intrusion, and its related faulting and surface deformation. We find that intrusions produce three different volcano deformation patterns, one of them involving asymmetric intrusion and deformation, with the early development of a listric slump fault producing pronounced slippage of one sector. This previously undescribed early deep potential slip surface provides a unified explanation for the two different eruptive scenarios (lateral vs. vertical). Lateral blast only occurs in flank collapse when the intrusion has risen into the sliding block. Otherwise, vertical rather than lateral expansion of magma is promoted by summit dilatation and flank buttressing. The distinctive surface deformation evolution detected opens the possibility to forecast the possible eruptive scenarios: laterally directed blast should only be expected when surface deformation begins to develop oblique to the first major fault.

Highlights

Large stratovolcanoes are unstable structures liable to massive, catastrophic flank failures, with more than 20 historical well-documented cases since 1500 AD1,2 and about 200 in the last 10,000 years[3]
It is not clear what controls why in some cases, a volcanic edifice can collapse when the magma body is still located at the volcano base, nor is the relationship of magma-induced deformation to the collapse structure clear
In order to achieve that objective we model the structural evolution of a stratovolcano at the first stages of viscous magma intrusion in the edifice to find out what controls landsliding

Summary

Introduction

Large stratovolcanoes are unstable structures liable to massive, catastrophic flank failures, with more than 20 historical well-documented cases since 1500 AD1,2 and about 200 in the last 10,000 years[3]. In order to achieve that objective we model the structural evolution of a stratovolcano at the first stages of viscous magma intrusion in the edifice to find out what controls landsliding We use this information to find the conditions that determine the likelihood of blast or only vertical eruption on collapse. A tube with a tap inserted vertically at the box base allows introducing the magma analogue (Golden Syrup), which flows by gravity due to the height difference between the box bottom and a syrup reservoir attached to the tube These experiments are designed to model the effect of viscous magma intrusion into a stratovolcano (see Methods), so they do not reproduce nor can be used to analyse other processes of deformation and volcano instability such as those related to the intrusion of fluid basaltic dykes in ocean island volcanoes[11]

Methods

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Conclusion