(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Figure 4: (a–h) GPR imaging of different depth (h = 0.05 m, 0.10 m, 0.20 m, 0.30 m, 0.40 m, 0.50 m, and 0.60 m).