Seismic refraction and traveltime tomography# 2D Refraction modelling and inversion 2D Refraction modelling and inversion Crosshole traveltime tomography Crosshole traveltime tomography Raypaths in layered and gradient models Raypaths in layered and gradient models Field data inversion (“Koenigsee”) Field data inversion ("Koenigsee") Refraction in 3D Refraction in 3D