heterogeneous structures, especially when the data quality is not very high. GAUTIER et al. perform tomographic inversion of local earthquake arrival times for crustal structure and earthquake locations in the actively rifting Gulf of Corinth. The velocities image the rift basin and the hypocenters image a regional-scale detachment fault. Inthe third group of papers, SNIEDER reviews theoretical concepts governing changes of coda waves due to small localized perturbations in the medium properties or source location, and describes how to estimatethe resulting meanand varianceofthe travel-time...