Seismic upgrades with sub-foundation pockets are an effective technique to increase the strength and stability of existing structures, particularly those with problems of subsidence or seismic vulnerability. This method involves the construction of localised excavations (pockets) under the existing foundations, which are then filled with reinforced concrete. The sub-foundation pockets allow the building's loads to be transferred to deeper and more stable soil layers, significantly improving the building's ability to resist seismic stress.

The intervention can also be supplemented by additional sub-foundation structures, such as kerbs and plinths, to increase stability in particularly critical cases