code: def _compute_mean(self, C, A1, A2, A3, A4, A5, A6, mag, hypo_depth,
                        rrup, mean, idx):
          
          mean[idx] = (A1 + A2 * mag + C['C1'] + C['C2'] * (A3 - mag) ** 3 +
                       C['C3'] * np.log(rrup[idx] + A4 * np.exp(A5 * mag)) +
                       A6 * hypo_depth)
docs: Compute mean for subduction interface events, as explained in table 2,
          page 67.