Volcanoes

There are more than 1,500 potentially active volcanoes or volcanic areas around the world at any given time. They may be the world’s most dynamic landforms, given their ability to grow by accretion or shatter and collapse during an eruption.
Volcanoes are vents in Earth’s crust capable of releasing molten rock (magma), hot rock fragments, and hot gases. Some volcanoes are prominent mountains or other land features that rise from islands or are nested within long mountain ranges, whereas others occur entirely underwater in ocean hotspots or at spreading centres along oceanic ridges. Some of the most destructive volcanoes in Earth’s history last erupted long before the development of civilization and writing, so the timing and effects of their activity must be inferred by investigating the landforms, rocks, and ash they left behind. However, the eruptive histories of many other volcanoes have been chronicled in written accounts that date back thousands of years.