code: def amplify_gmfs(imts, vs30s, gmfs):
      
      n = len(vs30s)
      out = [amplify_ground_shaking(im.period, vs30s[i], gmfs[m * n + i])
             for m, im in enumerate(imts) for i in range(n)]
      return numpy.array(out)
docs: Amplify the ground shaking depending on the vs30s