Fig. 4From: Adjoint-based direct data assimilation of GNSS time series for optimizing frictional parameters and predicting postseismic deformation following the 2003 Tokachi-oki earthquakeCost function. The blue line indicates the changes in the cost function values calculated using Eq. (7) with the number of iterations in Exp. 1. The red and green lines are those in Exps. 1-(i) and 1-(ii) mentioned in the “Discussion”Back to article page