Dépôt numérique

The effects of the host-substrate properties on maar-diatreme volcanoes: experimental evidence.

Macorps, Élodie; Graettinger, Alison H.; Valentine, Greg A.; Ross, Pierre-Simon; White, James D. L.; Sonder, Ingo (2016). The effects of the host-substrate properties on maar-diatreme volcanoes: experimental evidence. Bulletin of Volcanology , vol. 78 , nº 4. p. 26. DOI: 10.1007/s00445-016-1013-8.

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While the relationship between the host-substrate properties and the formation of maar-diatreme volcanoes have been investigated in the past, it remains poorly understood. In order to establish the effects of the qualitative host-substrate properties on crater depth, diameter, morphological features, and sub-surface structures, we present a comparison of four campaigns of experiments that used small chemical explosives buried in various geological media to simulate the formation of maar-diatremes. Previous results from these experiments have shown that primary variations in craters and sub-surface structures are related to the scaled depth (physical depth divided by cube root of blast energy). Our study reveals that single explosions at optimal scaled depths in stronger host materials create the largest and deepest craters with steep walls and the highest crater rims. For single explosions at deeper than optimal scaled depths, the influence of material strength is less obvious and non-linear for crater depth, and non-existent for crater diameter, within the range of the experiments. For secondary and tertiary blasts, there are no apparent relationships between the material properties and the crater parameters. Instead, the presence of pre-existing craters influences the crater evolution. A general weakening of the materials after successive explosions can be observed, suggesting a possible decrease in the host-substrate influence even at optimal scaled depth. The results suggest that the influence of the host-substrate properties is important only in the early stage of a maar-diatreme (neglecting post-eruptive slumping into the open crater) and decreases as explosion numbers increase. Since maar-diatremes reflect eruptive histories that involve tens to hundreds of individual explosions, the influence of initial substrate properties on initial crater processes could potentially be completely lost in a natural system.

Type de document:
Mots-clés libres: maar; diatreme; substrate; crater; morphology; phreatomagmatic
Centre: Centre Eau Terre Environnement
Date de dépôt: 20 déc. 2016 16:14
Dernière modification: 12 mai 2017 18:01
URI: http://espace.inrs.ca/id/eprint/3990

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