ALBERT

Description: The solar active regions are believed to be heated by magnetic disturbances propagating into the corona from the convection zone below. We use a reduced magnetohydrodynamic (RMHD) model of Alfven waves in a collection of 16 magnetic flux tubes. The waves are generated in the photosphere at the footpoints of the field lines and reflect at various positions along the loop, leading to counter-propagating waves and turbulence. We show that the turbulent Alfven waves heat the coronal loops to about 2- 3 MK temperatures. We measure the effects of Alfven wave turbulence on spectral line broadening from the RMHD model. The spectral line non-thermal widths predicted from the model of interacting field lines are about 27 km/s, consistent with the observations presented in this talk.

Description: For the efficient use of geothermal energy, especially for heat provision, energy must be provided close to a consumer structure, thus in urban areas. Exploration for potential reservoir or storage horizons and their microseismic monitoring during operation are, therefore, mandatory.For this purpose, the joint project SENSE tests seismic exploration and monitoring approaches based on fibre-optic sensing in urban areas using both active and passive seismic sources. To carry out the seismic measurements, a field-ready demonstrator is being built to carry out spatially distributed dynamic fibre-optic strain measurements. In addition to available instrumentation, strain changes with respect to a known reference are recorded, thereby also enabling the detection of long-term/quasi-static strain changes. This brings decisive advantages with regard to the detection of deep or long-wave signals as well as for the exclusion of very slow deformation movements in connection with the use of the geological subsurface.We exemplify the monitoring of borehole operations and the horizontal recording of the seismic wave field using cables in Berlin and Potsdam with the new developments tested. Processing workflows encompass shot gather extraction, and picking of dispersion curves that yield after inversion shear wave velocity models exposing several velocity interfaces. To this end, we expect that SENSE will deliver new options for urban monitoring also beyond geothermal.