code: def _apply_subduction_trench_correction(mean, x_tr, H, rrup, imt):
      
      if imt.name == 'PGV':
          V1 = 10 ** ((-4.021e-5 * x_tr + 9.905e-3) * (H - 30))
          V2 = np.maximum(1., (10 ** (-0.012)) * ((rrup / 300.) ** 2.064))
          corr = V2
          if H > 30:
              corr *= V1
      else:
          V2 = np.maximum(1., (10 ** (+0.13)) * ((rrup / 300.) ** 3.2))
          corr = V2
          if H > 30:
              V1 = 10 ** ((-8.1e-5 * x_tr + 2.0e-2) * (H - 30))
              corr *= V1
      return np.log(np.exp(mean) * corr)
docs: Implement equation for subduction trench correction as described in
      equation 3.5.2-1, page 3-148 of "Technical Reports on National Seismic
      Hazard Maps for Japan"