Collapse processes in abandoned pillar and stall coal mines: Implications for shallow mine geothermal energy

Flooded mine workings represent potential aquifers for shallow geothermal development projects. However, determining the collapse state of such workings in advance of drilling, and predicting their hydrogeological properties can be challenging, therefore developing an understanding of the products of mine collapse is important. We investigate the internal structure of collapsed pillar and stall mine workings exposed through coastal erosion near Whitley Bay, NE England. Our data suggests these workings collapsed in stages, leaving a clay-rich anthropogenic sedimentary layer consisting of collapse breccias and muds that will have gradually reduced the water capacity of the mine workings as collapse proceeded.