  We study the black hole interiors of spacetimes arising from gravitational
collapse in the spherically symmetric Einstein-scalar field setting, and we
investigate the precise blow-up rates of curvature and mass at the spacelike
singularity near timelike infinity. We show in particular that the Kretschmann
scalar blows up faster than in the Schwarzschild setting, due to mass
inflation. Moreover, the blow-up rate is not constant and converges to the
Schwarzschild rate towards timelike infinity and it depends on the precise
late-time polynomial behaviour of the scalar field along the event horizon.
This indicates a new blow-up phenomenon, driven by a PDE mechanism, rather than
an ODE mechanism.
