def _compute_focal_depth_term(self, C, rup):
        """
        Computes the hypocentral depth scaling term - as indicated by
        equation (3)
        """
        if rup.hypo_depth > 120.0:
            z_h = 120.0
        else:
            z_h = rup.hypo_depth
        return C['theta11'] * (z_h - 60.)