Wanderlust World Wanderlust World Volcanoes can form in many ways, and mostly occur along the edge of the tectonic plates that form the earth's crust. Many volcanoes occur when two plates move apart, allowing the magma to flow upward, which often happens underwater in oceans. Other volcanoes form when one plate moves under another, forcing the magma to the surface, where it becomes lava. Still others, called hot spot volcanoes, form when magma pushes its way to the surface in the middle of a plate.
The most visible and violent types are composite volcanoes, also known as strato-volcanoes, which form when a magma vent becomes blocked, forcing a gas and magma buildup that explodes under great pressure. A gentler type of volcano is the shield volcano, which occurs when liquid lava flows over a lower, less-angled surface. Other types of volcanoes include cinder cones, submarine volcanoes, and caldera volcanoes.
Many of the world's most visible volcanoes exist along the rim of the Pacific Plate, forming what is called the Ring of Fire. The ring includes the Pacific coast of North America and the east coast of China and Russia. Extending that area, the borders of the Cocos Plate and the Nazca Plate cause a line of volcanoes along the Pacific coasts of Central and South America. In addition, the Philippines Plate and the Caroline Plate border the Pacific Plate, causing volcanoes along the Asian coast.
Many volcanoes are tourist destinations; in these places, the layout of the land allows for safe viewing of eruptions. In Hawaii, Costa Rica and Nicaragua, travelers watch glowing lava flow down the sides of tall volcanoes. Many other volcanoes, such as Mount St. Helens in Washington, are popular for hiking and scenic views.
The most remembered volcanoes are those with a violent past. in 79 AD, Mount Vesuvius in Italy destroyed the cities of Pompeii and Herculanum with one eruption; historians estimate that the eruption killed between 10,000 and 25,000 people. At Mount St. Helens, an eruption caused mass destruction and death in 1980. Volcanoes can bathe an area in ash and lava, killing humans and affecting weather patterns for a wide radius.