How long does it take for a volcanic island to form?

Answer 1

it takes 30 minutes for a volcanoe to form. its probly safer than an earthquake because volcanoes actually give you time to move or leave the place.

++++

That first sentence's first clause is just Not True (and the time quoted wilfully stupid) though yes, a volcano often warns of an impending eruption so giving you time to move to safety.

The problem is that the answer above is trying to answer a meaningless question posed by someone who clearly has not grasped the essential nature of geological features generally - their unique, long-term existences over vast spans of time, within their own types or classes. So a volcano's growth rate is unique and its active life, or that of the group in a single cluster / range of related volcanoes, may span millions of years.

Answer 2

Volcanoes are created over approximately 10,000-500,000 years by thousands of eruptions -- each lava flow covering the one before it. In the case of oceanic island volcanoes, lava erupts first from fissures, or cracks, on the deep ocean floor. The flows continue to build up and finally an island emerges from the sea. It was only when scientists began sampling the deep ocean floor in the 1950s and 1960s that they realized that most of the ocean floor is composed of lava flows. In fact, more lava has erupted on the sea floor than anywhere on Earth, mostly from mid-ocean ridges -- the longest chain of active volcanoes on our planet.

Answer 3

Yes (very!), Hot liquids come up from deep underground, cools and hardens. This process happens 100s of times to form a volcanoe