It is not the volcano that “decides” to become extinct, and then the magma chamber, now no longer needed, has to determine how it will handle the situation, but the exact opposite. Instead, it is... ... As the plate moved, each of the volcanos on the former islands grew less active, then silent, and are now considered extinct. read more
In time, the volcano becomes large enough to break the surface of the ocean and islands form from the cooled lava. Tectonic plates move regularly and as such, so do the volcanoes that form. When undersea volcanoes become extinct before breaking the surface, they form mounds that are known as seamount chains. read more
There are three ways to describe a volcano’s activity; there can be active, dormant, or extinct volcanoes. Active volcanoes have erupted recently. A dormant volcano isn’t erupting right now, but vulcanologists expect it could erupt at any time. read more
Volcanoes go dormant because magma from the Earth's mantle can no longer reach the volcano. For example, in Hawaii, the line of islands are slowly moving to the northwest. Meanwhile, the supply of magma stays in the same place within the Earth, which currently happens to lie beneath the Big Island. read more