code: def get_mean_and_stddevs(self, sites, rup, dists, imt, stddev_types):
          
          # fix hypocentral depth to 20 km. Create new rupture context to avoid
          # changing the original one
          new_rup = copy.deepcopy(rup)
          new_rup.hypo_depth = 20.
  
          mean, stddevs = super().get_mean_and_stddevs(
              sites, new_rup, dists, imt, stddev_types)
  
          return mean, stddevs
docs: See :meth:`superclass method
          <.base.GroundShakingIntensityModel.get_mean_and_stddevs>`
          for spec of input and result values.
  
          Call super class method with hypocentral depth fixed at 20 km