Researchers combined high-resolution three-dimensional seismic tomography with laboratory rock-physics experiments on deep-well samples to image Campi Flegrei’s subsurface to approximately 4 kilometers. The analysis identified a major crustal transition at about 2.5–2.7 kilometers and a weak tuff layer extending roughly 3–4 kilometers deep. Earthquakes greater than magnitude 3 are concentrated above this layer, at approximately 2–3 kilometers, where geological evidence indicates repeated magma-dike intrusion.[1][2][4]
The structure comprises a gas-rich reservoir below 2 kilometers, a deformed caprock at 1–2 kilometers, and basement below 3.5 kilometers. The mapped seal horizon is approximately 1 kilometer thick; laboratory results indicate caprock failure at stresses of roughly 45–74 MPa. The finding shows that seismic unrest and surface deformation can be governed by concealed interfaces that trap fluids and focus stress, rather than by a single visible magma chamber.[5]
The Ark should integrate multiscale subsurface tomography, borehole-derived rock physics, and continuous microseismic monitoring into lunar-site qualification. Design reviews should explicitly map weak layers, buried voids, volatile reservoirs, and stress-concentration boundaries beneath habitats, tunnels, and stores; monitoring thresholds should be tied to measured material strength and fracture evolution rather than surface motion alone. The same workflow should support periodic re-imaging after excavation, impacts, thermal cycling, or pressurization changes.