Eruption of Mount Vesuvius, 79 AD

plate tectonics

In this lesson, we'll explore the magic behind the mayhem. After all, this kind of thing doesn't happen for no reason at all.

Let's start with the basics. We are just walking around on the scum floating on top of the pond, the icebergs covering a vast ocean. To be more precise, the surface of the Earth is composed of thin plates of hardened rock, drifting upon the giant ball of molten rock and metal that comprisies most of the planet.
Cross-section of our planet
Above we see a cross-section (not to scale) of our planet. The white layer is the atmosphere. The brown layer is the crust, the red layer is the mantle, and the orange and yellow are the inner and outer cores, respectively. The mantle itself is divided into many different layers:

For our purposes, "The rest of the Mantle" is as specific as we need to be.

The Asthenosphere really is that bumpy. Here is another diagram.

The Lithosphere is broken into many individual plates. Here is a map of the them:

Plate boundaries fall into three categories:

The three categories are: transform (side-by-side), divergent (pulling apart) and convergent (moving towards each-other.) Convergent boundaries are further divided into colliding (both plates are pushing up to form mountains) and subducting (one plate going under another to form a trench.)


Continental-Oceanic-Convergent             Oceanic-Oceanic-Convergent

There are two types of plates: continental and oceanic. Continental plates tend to float higher than oceanic plates. Therefore, Continental-Continental-Convergent boundaries tend to be colliding boundaries, while Continental-Oceanic-Convergent and Oceanic-Oceanic-Convergent boundaries tend form subduction zones.

The power that fueled Mount Vesuvius was formed from the subduction of the African plate beneath the Eurasian plate. We'll discuss this in the next exciting webpage.
Go to the next page.


-Main page

-Plate tectonics

-The setting

-THe cause

-The disaster

-The aftermath