We prove a logarithmic stability estimate fora parabolic inverse problem concerning the localization of unknowncavities in a thermicconducting medium Ω in  ${\mathbb R}^n$  , n ≥ 2, from a singlepair of boundarymeasurements of temperature and thermal flux.
 , n ≥ 2, from a singlepair of boundarymeasurements of temperature and thermal flux.