diff --git a/examples/03_checkerboard_2d/plot_model.ipynb b/examples/03_checkerboard_2d/plot_model.ipynb
index a7c247b..7f024bc 100644
--- a/examples/03_checkerboard_2d/plot_model.ipynb
+++ b/examples/03_checkerboard_2d/plot_model.ipynb
@@ -11,24 +11,6 @@
     "import numpy as np"
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": 34,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "def to_ani(xi, eta):\n",
-    "    epsilon = np.sqrt(eta**2+xi**2)\n",
-    "    phi = np.zeros_like(epsilon)\n",
-    "    idx = np.where(xi <= 0)\n",
-    "    phi[idx] = 90 + 0.5*np.rad2deg(np.arctan(eta[idx]/xi[idx]))\n",
-    "    idx = np.where((xi > 0) & (eta <= 0))\n",
-    "    phi[idx] = 180 + 0.5*np.rad2deg(np.arctan(eta[idx]/xi[idx]))\n",
-    "    idx = np.where((xi > 0) & (eta > 0))\n",
-    "    phi[idx] = 0.5*np.rad2deg(np.arctan(eta[idx]/xi[idx]))\n",
-    "    return epsilon, phi\n"
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": 35,
@@ -40,11 +22,6 @@
     "    x = f['x'][:]\n",
     "    y = f['y'][:]\n",
     "    periods = f['periods_ph'][:]\n",
-    "    xi = f['xi_ph'][:]\n",
-    "    eta = f['eta_ph'][:]\n",
-    "    epsilon, phi = to_ani(xi, eta)\n",
-    "with h5py.File('OUTPUT_FILES/model_iter.h5', 'r') as f:\n",
-    "    svel0 = f['vel_rayleigh_000'][:]\n",
     "xx, yy = np.meshgrid(x, y)\n"
    ]
   },
@@ -73,7 +50,7 @@
     "region=[x.min(), x.max(), y.min(), y.max()]\n",
     "fig = pygmt.Figure()\n",
     "fig.basemap(region=region, projection='M4i', frame=True)\n",
-    "grid = pygmt.surface(z=eta[:,:,num_period].ravel(), x=xx.ravel(),y=yy.ravel(), region=region, spacing='0.01/0.01')\n",
+    "grid = pygmt.surface(z=svel[:,:,num_period].ravel(), x=xx.ravel(),y=yy.ravel(), region=region, spacing='0.01/0.01')\n",
     "fig.grdimage(grid=grid, cmap='seis')\n",
     "fig.show()"
    ]