It is believed that the lighter eruptions happened over several months rather than only hours before the main eruption.

We know this because geologists found a layer of ash that they determined had been exposed to air before the major layer of pumice that eventually followed. Now, that is impressive science!

Perhaps the long eruption time of the early ash events allowed for people on Santorini to decide to leave, while those in Pompeii who only saw eruptions for a few hours did not. We will probably never know for sure.

One of the reasons we can’t be sure about this is that the next volcano we’ll talk about had people living nearby who chose not to run away from a volcano specifically because it had been erupting for weeks and weeks. Go figure.

This photograph was taken from the International Space Station. It shows a volcano on the Island of Sicily, erupting on July 22, 2001. In the photo you can see the long gray plume of ash that is being carried by the wind.