| Title | Magnetotelluric investigation of the Northern Swiss Heat Flow Anomaly |
|---|---|
| Authors | Samrock, F; Shah, N; Saar, M |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Magnetotellurics, electrical conductivity, Northern Switzerland, heat flow anomaly |
| Abstract | The North of Switzerland hosts a prominent heat flow anomaly, with an enhanced near-surface heat flux compared to the Swiss average. The anomaly is situated within the permo-carboniferous trough and one hypothesis about its origin is that geothermal fluids migrate upwards along permeable pathways, carrying heat from the crystalline basement into shallower layers. We performed a magnetotelluric (MT) survey covering the extent of the anomaly over the permocarboniferous trough. In order to overcome the noise problem related to power-lines and local infrastructure we tested different processing methods using multiple remote reference sites and discuss the feasibility of MT measurements in densely populated regions. Ultimately, MT responses are planned to be inverted for a 3-D conductivity model using state-of-the-art inverse solvers, which have been recently developed at ETH Zurich. Besides the impedance tensor, which is the standard MT response, we interpret newly introduced inter-site transfer functions, which are free of galvanic distortion effects such as static shifts. A recovered 3-D resistivity model could help to determine the geometry of the permo-carboniferous trough and to identify permeable structures within it and the crystalline basement. These results would provide important information about the nature and origin of the heat flow anomaly. |