ALBERT

Description: Unravelling the internal structure of volcanoes is an essential step to understand the architecture of the magmatic system and advance hazard assessment. Electromagnetic (EM) measurements are particularly suited for this task due to the high contrast in resistivity between melts and solid rock. Due to this, EM surveys of active volcanoes have gained significant attention in recent years. However, many modelling and inversion algorithms only provide a rough approximation of the significant topography of the volcanoes. Currently it is not clear to which level the topography has to be incorporated to provide reliable and robust results. We use two modern finite-element modelling algorithms for magnetotelluric data to assess the impact of different approximations. Based on the geometry of a recent survey at Mt. St Helens we will compare the results of the two algorithms with different topography approximations. We will discuss different strategies for incorporating topography and how to ensure valid calculations of magnetotelluric forward responses.

Description: Magnetotellurics (MT) is widely used to image volcanic regions' three-dimensional (3-D) electrical conductivity structures. This requires a robust modeling solver which can deal with models with large conductivity contrast between melts and solid rock as well as topography. To this end, we developed a parallel 3-D MT forward modeling tool using the adaptive finite element method based on the open-source and scalar C++ library called the modular finite element method (MFEM). Tetrahedral grids were adopted to discretize the whole modeling domain, which can deal with complex underground structures with arbitrary topography. The flexible generalized minimum residual solver (FGMRES) with an auxiliary Maxwell solver pre-conditioner was applied to solve the final large-scale system of linear equations. We performed several experiments on synthetic models to verify the accuracy and efficiency of the developed tool. Then, we applied the tool to calculate the MT responses (impedance and tipper) at Mount St. Helens taking into account topography in the modeling to demonstrate the capability of the developed tool for dealing with complex models. The tool will be incorporated into the inversion tool JIF3D and substantially open-access.

Description: Detection of geophysical signatures associated with a geologic event, such as a volcanic eruption, is key to understanding the underlying physical processes and making an accurate hazard assessment. Magma reservoirs are the main repositories for eruptible magma, and understanding them requires the ability to detect and interpret changes in the magmatic system from surface measurements. Traditionally, monitoring for these changes has been done with seismic and geodetic approaches, both of which require dynamic ‘active’ changes within the magmatic system. Neither of these techniques is sensitive to the petrology or temperature of the magma though. Thus, additional monitoring techniques able to detect ‘static’ phase changes in the evolving magma and the thermal structure of the magma reservoir are needed. The magnetotelluric method, measures subsurface electrical properties and is sensitive to both ‘magma on the move’ and petrological changes that occur within the magma reservoir. Using Mount St Helens where a detailed magnetotelluric survey was completed during the most recent dome building eruptive phase 2005-06, and is now in a period of quiescence, we compare the original measurements to repeated measurements in the same locations in 2022 to develop temporal analysis approaches required for monitoring. In addition to the repeat campaign we have deployed 4 long-term continuous monitoring stations with telemetry to local servers. First, qualitative, comparisons of the data from different time periods indicate some significant changes in subsurface conductivity. We present an overview of the newly acquired data and the monitoring setup and discuss where the most significant changes occur.

Description: The Cascade arc runs from Southern British Columbia through Northern California and developed by the subduction of the Juan de Fuca plate beneath North America. Among the volcanoes of the Northern Cascades, Mount St Helens (MSH) is the most active.Inter-connected melt within the underlying magmatic systems of volcanic regions allow identification of the system via Magnetotelluric (MT) imaging due to the sensitivity of the method to electrical conductivity. Time variance of the properties of the melt due to changes in eruptive activity may result in significant conductivity changes that can be identified with continuous MT monitoring. Galvanic distortions resulting from the small near-surface conductivity variations may can be difficult to separate from the expected subtle observational differences. However, impedance phase relations in MT are free of these galvanic distortions. Thus, by exploiting changes in the phase response (the MT Phase tensor), it is possible to identify the temporal conductivity changes associated with changes occurring within the magmatic system.Prior MT results in the Washington cascades show a significant conductive anomaly underneath the MSH attributed to be partial melt supplying the volcano. With the aim of revealing conductivity changes beneath MSH, both a campaign style reoccupation of measurements completed during the 2004-2008 dome building eruption, and installation of four ‘continuous’ monitoring MT stations has been completed. Among the new MT dataset, a preliminary comparative phase tensor analysis of 56 repeated measurements identifies conductivity changes at frequencies that correlate the depth of the partial melt within the magmatic system.

Description: Recent supercomputing power improvements enable us to explore climate variability and change with coupled models that resolve the ocean mesoscale, its fine-scale interactions and feedbacks. Although these processes are usually parametrised in standard resolutions, several studies have already shown that effectively resolving them leads to reduced model biases in the ocean and improved air-sea interactions. In this study, we have used control simulations with the global climate model EC-Earth3P following the HighResMIP protocol to investigate the role of fine-scale processes in large-scale ocean circulation in the Atlantic. In particular, we have worked with three configurations of the model: eddy-parameterised (~100 km nominal horizontal resolution in mid-latitudes), eddy-permitting (~25 km) and eddy-resolving oceans (~10 km). For each model configuration, we have studied the two leading modes of variability of the mixed-layer depth in the subpolar North Atlantic. We have explored their drivers and preconditioners (which include the background stratification, the local buoyancy forcing from the atmosphere, and the advection of salinity and temperature anomalies by the mean circulation). We have also investigated whether and how they eventually impact the variability of the Atlantic Meridional Overturning Circulation (AMOC) through their influence on the southward propagation of density anomalies along the western boundary current.

Description: The study of global phenomena such as the impact of the oceans on climate change requires extensive and high-quality data. Over the last decade underwater observatories became a mature technology, allowing the collection of high-resolution data on a continuous basis. However, the management of such large volumes of heterogeneous data proves to be a challenge. This work presents the OBSEA’s underwater observatory data management e-Infrastructure. This infrastructure leverages existing open-source tools and community-accepted standards to build a modular yet robust data management framework, supporting the storage and exchange of multi-parametric marine data following the FAIR principles.