Several alternative gravity modelling techniques and associated numerical codes with their own advantages and limitations are available for the solid Earth community. With upcoming state-of-the-art lithosphere density models and accurate global gravity field data sets, it is vital to understand the differences of the various approaches. In this paper, we discuss the four widely used techniques: spherical harmonics, tesseroid integration, triangle integration, and hexahedral integration.

Volcanic eruptions are controlled by the presence of gas bubbles in magma, which, in excess, can cause explosions. Eruption models lack an understanding of how gas percolates in magma flowing in a conduit. Here we study gas percolation in magma associated with the 1994–1995 eruption at Mt. Unzen, Japan. The results show that the pathways for gas escape depend on the depth and ascent rate of magma. Pathways closed at depth but opened along fractures when magma ascended rapidly near the surface.

Triaxial compression tests at different effective stresses allow for analysing the deformation behaviour of Opalinus Clay, the potential host rock for nuclear waste in Switzerland. We conducted microstructural investigations of the deformed samples to relate the bulk hydro-mechanical behaviour to the processes on the microscale. Results show a transition from brittle- to more ductile-dominated deformation. We propose a non-linear failure envelop associated with the failure mode transition.

Methods for mineral exploration play an important role within the EU. Exploration must be environmentally friendly, cost effective, and feasible in populated areas. Seismic methods have the potential to deliver detailed images of mineral deposits but suffer from these demands. We show the results for a sparse 3D seismic dataset acquired in Sweden. The 3D depth image allows us to track the known mineralizations beyond the known extent and gives new insights into the geometry of the deposit.