Fig. 4

Critical fracture energy step, \({\gamma }_{c}\), for the anti-plane case, plotted against different fault parameters. The obtained \({v}_{i}\) values are color-coded in each plot. a \({\gamma }_{c}\) for three different \(\xi\) values (0.33, 0.48, and 0.80) using a fixed \({\sigma }_{p}\) value (14 MPa), and a range of \({\sigma }_{0}\) and \({D}_{C}^{\prime}\) values. b \({\gamma }_{c}\) for the same three \(\xi\) values using a fixed \({\sigma }_{0}\) value (3 MPa), and a range of \({\sigma }_{p}\) and \({D}_{C}^{\prime}\) values. c \({\gamma }_{c}\) for a range of \(\xi\) values. All of the cases in (a) and (b) are also plotted as black triangles (\(\xi\) = 0.33, 0.48, and 0.80) in (c). Although we observe slight variations between (a) and (b), this is not significant in the global variation in (c)