Rapid gas depressurization leads to gas cooling followed by slow gas warming when the cavern is kept idle. Gas temperature drop depends upon withdrawal rate and cavern size. Thermal tensile stresses, resulting from gas cooling, may generate frac-tures at the wall and roof of a salt cavern. These fractures are perpendicular to the cavern wall; in most cases their depth of penetration is small. The distance between two parallel fractures becomes larger when fractures penetrate deeper in the rock mass, as some fractures stop growing. These conclusions can be supported by numerical computations based on fracture mechanics. Salt slabs are created. These slabs remain strongly bounded to the rock mass and it is believed that in many cases their weight is not large enough to allow them to break off the cavern wall. However, depth of penetration of the fractures must be computed to prove that they cannot be a concern from the point of view of cavern tightness.