Sound waves are waves of growing larger and smaller, making it seem elastic through substances, such as air.
<span>There are more than 550 active
volcanoes in the world, almost all of which are located at convergent
tectonic plate boundaries. This includes all of the volcanoes in the
Pacific Ring of Fire, such as Japan's Mount Fuji, as well as Mount Saint
Helens, Popocafepetl in Mexico and Azul in the Andes Range.</span>
