Volcanic eruptions that occur as a result of continental shifting are typically found where
the crust is thickened and the tectonic plates converge.
the crust is thinned and the tectonic plates diverge.
the crust diverges and the tectonic plates submerge.
the crust emerges and the tectonic plates converge.

the crust is thinned and the tectonic plates diverge.  

Divergent boundaries are formed when two plates namely continental and oceanic plates diverges or separates. The oceanic plate being lighter in weight exhibit thin crust subducts at the bottom where the magma from the mantle causes the subducted plate to melt and lifted . The magma rises up forms cracks in subducted plate. The magma erupt as undersea volcanoes. The magma cools down and forms a raised ridge called a mid-ocean ridge.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave