ALBERT

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: Resistivity is a physical parameter sensitive to the existence and connectivity of the crustal fluids and melts. In this paper, we present a 3-D resistivity model covering an area of 50km x 50km in the central part of the NE Japan volcanic arc. We have compiled wide-band magnetotelluric data, which were collected over 30 years. We used full impedances and tippers of the 410 stations between 0.4 and 1,300s periods. The final model shows the existence of a continuous low resistivity belt in the SSW-NNE direction along the volcanic arc in the deep crust (20 km to 30 km depth). On the forearc side, we also see a distribution of low resistivity anomalies, which imply fluid upwelling. These low resistivity anomalies in the deep crust correspond to strain-concentration areas along the volcanic arc and the forearc. The low resistivity zone along the volcanic arc locally shallows to a depth of 10 km, branching toward active quaternary volcanoes, such as Naruko volcano, Mt. Kurikoma, Onikobe caldera, and Takamatsu-dake. These swallow anomalies below the volcanoes imply magmatic melt and correlate well with the co-seismic subsidence zones due to "2011 off the Pacific coast of Tohoku earthquake" detected by InSAR.

Description: A new ground-based optical observation of aurora and airglow in short-wavelength infrared (SWIR) of 1.05-1.35 μm has been initiated at The Kjell Henriksen Observatory (KHO), Longyearbyen (78.1°N, 16.0°E) since November 2022. Two state-of-the-art instruments, a SWIR imaging spectrograph and a monochromatic imager, are being operated to focus on study on dayside magnetosphere-ionosphere-atmosphere coupling processes in the high polar regions.The 2-D imaging spectrograph, NIRAS-2, measures SWIR auroral emissions such as N2+ Meinel band (0,0), N2 1st Positive bands (0,1), and OI- line with time resolution of 30 seconds. Using high spectral resolution mode, N2+ ion rotational temperature would be estimated. For upper mesosphere, OH (8,5) band was measured and its rotational temperature can be estimated with10-min resolutions and errors less than 5 K. In addition, one more important thing is that this OH emission band is almost completely uncontaminated by aurora. On the other hand, the brand-new SWIR camera, NIRAC, can visualize two-dimensional structures of not only aurora (N2+) but also even weak airglow (OH) with a cadence of less than 30 seconds. This is the monochromatic imaging of SWIR aurora for the first time so far, and the NIRAC is used as a twin instrument to the NIRAS-2 to help in interpreting meridional scan data obtained from the NIRAS-2. Taking geographical advantage of the observatory, 24-hours continuous observations can be expected near the winter solstice. Initial results of NIRAS-2 and NIRAC are presented and then we will discuss the observational strategies and future collaborations.

Description: The conversion of the electromagnetic energy into the heat through the ohmic current is well known as the Joule heating. The Joule heating process plays an important role in dictating the solar wind energy propagation within the magnetosphere-thermosphere-ionosphere system during space weather events. It drives large vertical velocity altering the global circulation patterns and modifies the thermospheric structure, chemistry and dynamics including the global and local enhancement in thermospheric temperature. The thermospheric radiative emission by Nitric Oxide (NO) at 5.3 µm effectively regulates the thermospheric temperature during space weather events. In addition, the NO at 5.3 µm radiative emission accounts for about 80% of Joule heating energy during geomagnetic storms. We utilize the NO radiative emission at 5.3 µm as observed by the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument onboard the NASA’s TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite and the Joule heating rates derived from the EISCAT (European Incoherent Scatter) radar to investigate the storm-time impacts of Joule heating on the NO 5.3 µm cooling emission. Furthermore, we also quantify the spatial and temporal variations of the Joule heating and their relation and cross-correlation with the thermospheric cooling emission during the geomagnetic storms of different intensity.

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: The solar energy deposited into Earth’s magnetosphere-ionosphere-thermosphere (MIT) system, during the geomagnetic storms, significantly perturbs the thermospheric structure, chemistry and energetics. This energy is dissipated due to the Joule heating and thermospheric cooling mechanisms by Nitric Oxide (NO) via 5.3 µm and Carbon Dioxide (CO2) via 15 µm. The latter processes effectively regulate the thermospheric temperature and are well known as natural thermostat. We utilize the NO at 5.3 µm and CO〈sub〉2〈/sub〉 at 15 µm radiative emissions as observed by the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument onboard the NASA’s TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite to investigate the response of the magnetosphere-ionosphere-thermosphere system to the geomagnetic storms of different solar origin. It is observed that both the magnitude and temporal variations of the radiative cooling processes strongly depend on the solar origin of the geomagnetic storm. We exploit the particle flux as measured by the DMSP (Defense Meteorological Satellite Program) satellite, the GRACE (Gravity Recovery and Climate Experiment) satellite observations of atmospheric density, and solar wind-magnetosphere coupling functions from the SuperMAG database to explore the possible mechanisms responsible for the distinctive behaviour.

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.