Disputation: Håvard Svanes Bertelsen
Doctoral candidate Håvard Svanes Bertelsen at the Department of Geosciences, Faculty of Mathematics and Natural Sciences, is defending the thesis "Beyond Elasticity - An Experimental Study of Magma Emplacement Mechanisms and Associated Deformation Structures" for the degree of Philosophiae Doctor.
Håvard Svanes Bertelsen. Photo: Private
Trial lecture - time and place
Friday 25 October, 10:15–11:00, Auditorium 3, the ZEB building:
Interaction of Volcanoes and Earthquakes
Conferral summary (in Norwegian)
Magmatiske intrusjoner tvinger seg fram gjennom jordskorpen ved å lage sprekker og ganger, og hvordan denne oppsprekkingen skjer er et grunnleggende spørsmål for å forstå vulkanisme. I sin avhandling utforsker Bertelsen forskjellige intrusjonsmekanismer gjennom laboratoriemodeller. Avhandlingen gir ny innsikt i sammenhengen mellom intrusjonsmekanismer og deformasjonsstrukturer som oppstår i jordskorpen og på overflaten, og setter spørsmålstegn ved modeller som brukes for å tolke vulkansk overflatedeformasjon i dag.
Main research findings
Popular scientific article about Bertelsen’s dissertation:
How does host rock deformation relate to magmatic emplacement in the Earth’s crust?
This thesis aims to bring new physical understanding of magma emplacement mechanisms and associated host rock deformation structures. The study used laboratory models of magma intrusions in crustal analogues of different rheologies where deformation was monitored in high resolution.
We describe one elastic and one plastic emplacement mechanism that both produce dykes of similar shapes, but with distinct surface deformation patterns. We show intrusion experiments in a visco-elasto-plastic crustal rheology that reproduce the diversity of intrusion shapes and deformation structures seen in nature.
The observed richness of structural expression is chiefly controlled by the rheological contrast between the magma and the crust, but also by small-scale heterogeneities enhancing failure localization and stochastic behaviour. Contrary to consensus, small-scale plastic deformation at the intrusion tip was found to have large impact on large-scale deformation. The presented work challenges the elastic crust assumption in current geodetic models, and we find it essential to account for the heterogeneity and complex rheology of the Earth’s crust to fully understand magma emplacement processes.
Photo and other information:
Press photo: Håvard Svanes Bertelsen (portrait)
Other photo material: Polariscope_photo_of_viscous_oil_intruding_into_elasto-plastic_laponite. Photo: B. D. Rogers / H. S. Bertelsen.