Experiments with vertically and laterally migrating subsurface explosions with applications to the geology of phreatomagmatic and hydrothermal explosion craters and diatremes

Abstract : We present results of experiments that use small chemical explosive charges buried in layered aggregates to simulate the effects of subsurface hydrothermal and phreatomagmatic explosions at varying depths and lateral locations, extending earlier experimental results that changed explosion locations only along a vertical axis. The focus is on the resulting crater size and shape and subcrater structures. Final crater shapes tend to be roughly circular if subsurface explosion epicenters occur within each other’s footprints (defined as the plan view area of reference crater produced by a single explosion of a given energy, as predicted by an empirical relationship). Craters are elongate if an epicenter lies somewhat beyond the footprint of the previous explosion, such that their footprints overlap, but if epicenters are too far apart, the footprints do not overlap and separate craters result. Explosions beneath crater walls formed by previous blasts tend to produce inclined (laterally directed) ejecta jets, while those beneath crater centers are vertically focused. Lateral shifting of explosion sites results in mixing of subcrater materials by development of multiple subvertical domains of otherwise pure materials, which progressively break down with repeated blasts, and by ejection and fallback of deeper-seated material that had experienced net upward displacement to very shallow levels by previous explosions. A variably developed collar of material that experienced net downward displacement surrounds the subvertical domains. The results demonstrate key processes related to mixing and ejection of materials from different depths during an eruptive episode at a maar-diatreme volcano as well as at other phreatomagmatic and hydrothermal explosion sites.
Document type :
Journal articles
Complete list of metadatas

https://hal.uca.fr/hal-02115266
Contributor : Sylvaine Jouhannel <>
Submitted on : Tuesday, April 30, 2019 - 10:44:20 AM
Last modification on : Thursday, November 21, 2019 - 2:11:53 AM

Identifiers

Collections

Citation

Greg Valentine, Alison Graettinger, Élodie Macorps, Pierre-Simon Ross, James White, et al.. Experiments with vertically and laterally migrating subsurface explosions with applications to the geology of phreatomagmatic and hydrothermal explosion craters and diatremes. Bulletin of Volcanology, Springer Verlag, 2015, 77 (3), ⟨10.1007/s00445-015-0901-7⟩. ⟨hal-02115266⟩

Share

Metrics

Record views

44