There's a gentleman who came across my radar, who follows this kinda stuff much like a 'storm chaser' might in the US. He has a recent (Wednesday) video where he found hotspots on the surface with a thermal camera - close enough to the Blue Lagoon that it's in-frame. https://www.youtube.com/watch?v=KV75cDceExw&t=115s

It's worth noting the area is surprisingly flat. Flat like sandpaper - it's not at all smooth, but there's not much of a gradient either. Essentially whatever the volcanic version of a flood plain is. So a surface fissure here could be quite problematic. It's very close to the power station, very close to the resort, and there's not a lot of geography to channel it away.