Complex sentence: The central region is from 3 ° S-2 ° N. In the area near Simeulue island (2-2.5 ° N), the prism narrows greatly with the increasing of average surface slope.
Split into simpler sentences: The central region is from 3 ° S-2 ° N in the area near Simeulue island (2-2.5 ° N). The prism narrows greatly with the increasing of average surface slope.