Geophysical observations provide insight into the deformation processes of the Earth’s upper crust induced by magma propagating towards the surface below active volcanoes. It is however impossible to directly observe these processes in the subsurface, and therefor volcanologists rely on a series of assumptions to construct theoretical and numerical models. To investigate assumptions regarding the geometrical development of magma intrusions and the related fracturing mechanisms in their host rocks, we developed a novel approach of imaging scaled laboratory experiments by using medical, broad beam X-ray Computed Tomography (CT) at the UZ Brussel. A temporal series of 3D scans is therein acquired by CT during injection of golden syrup – a magma analogue – into dry mixtures of quartz sand and gypsum powder – a brittle rock analogue. Extraction of the analogue intrusion geometry using image segmentation algorithms at a series of time steps then allows to study the geometrical growth of the analogue intrusions and deformation structures (i.e. fractures, faults) in the host material. New Matlab scripts further allow extraction of the model surface syn-intrusion, which allow direct comparison with surface displacement data collected at active volcanoes. Furthermore, Digital Volume Correlation (DVC) in the DaVis software (LaVision) is used to quantify the analogue magma-induced displacement and strain fields, which are then quantitatively analysed using dedicated Matlab scripts. The major novelty of our approach is that it extends 4D monitoring and quantification of deformation beyond the model surface deformation by enabling a full quantification of the analogue intrusion growth and related host rock deformation. By producing such unprecedented data off the experiments, we found that host rock strength controls intrusion geometry and propagation mode. Comparison with geophysical monitoring data from recent magma intrusion events, challenges the physical relevance of currently used conceptual models that are used to estimate subsurface magma intrusion geometries, and ultimately contributes to strengthening volcano eruption forecasts.
Original languageEnglish
Publication statusPublished - Sep 2019
EventMBL-OPTIMESS 2019 Conference - University of Antwerp, Antwerp, Belgium
Duration: 18 Sep 201920 Sep 2019
https://www.uantwerpen.be/en/conferences/optimess/about/

Conference

ConferenceMBL-OPTIMESS 2019 Conference
CountryBelgium
CityAntwerp
Period18/09/1920/09/19
Internet address

ID: 47159146