How long does it take for the lava to flow out of the center of the Earth and to erupt out of the volcano and become igneous rock?

Dear J.M.,

I can see you like volcanoes. So do I! They are an awesome part of God's creation. Volcanoes are mountains that have pools of molten rock inside. Eventually, pressure builds up until it has to find somewhere to escape. It then forces its way up through "fissures," which are cracks in the Earth's surface. Once the hot magma passes through the Earth's surface, it is called lava. Igneous rocks form whenever the lava cools down and turns into rock. 

How long does this process take? It certainly does not take millions of years. The fact of the matter is, there is no certain amount of time that it takes volcanoes to erupt. Some very active volcanoes can erupt every few months. Mt. Etna, in Sicily, is an example of this kind of volcano. Other volcanoes erupt every 5-10 years. And some volcanoes may erupt once in a thousand years. We do know that most of the time, the volcanoes that erupt often are much smaller and produce small explosions and ash clouds. But the ones that take longer to erupt have time to build up more force and erupt in much larger explosions. Thanks for your good question.