Anthropogenic thermogeological ‘anomaly’ in Gateshead, Tyne and Wear, UK

Two subsurface thermal profiles were measured in geothermal ‘closed-loop’ boreholes at Gateshead, Tyne and Wear, UK. They show a clear reversed gradient (temperature decreases with depth) down to at least 55 m, and the subsurface temperatures are generally warmer than those predicted purely from annual average soil temperature data and the known geothermal heat flux. This suggests that historical downward conductive heat ‘leakage’ from the long-established Gateshead urban environment has modified subsurface temperatures to depths of at least 55 m. Although poorly documented in the UK, a similar ‘urban thermogeological heat island’ effect has been noted from Canada, Sweden, Ireland and Japan.