def get_mean_and_stddevs(self, sites, rup, dists, imt, stddev_types):
        """
        See :meth:`superclass method
        <.base.GroundShakingIntensityModel.get_mean_and_stddevs>`
        for spec of input and result values.
        """
        mean, stddevs = super().get_mean_and_stddevs(sites, rup, dists, imt,
                                                     stddev_types)
        delta = self._get_delta(imt, rup.mag)
        return mean-delta, stddevs
See :meth:`superclass method
        <.base.GroundShakingIntensityModel.get_mean_and_stddevs>`
        for spec of input and result values.