Question: Is it possible for tectonic plates to split in two?

Natasha Dowey answered on 4 Mar 2019: last edited 4 Mar 2019 4:43 pm

This is a really great question. Put simply, yes!

The Earth’s crust is split into tectonic plates, that sit upon (and move about on) a layer of very hot rocks called the ‘mantle’. The rocks in the mantle are so hot they can move and deform, a bit like melting plastic. The way our tectonic plates are currently set up hasn’t always been the same. Throughout hundreds of millions of years, tectonic plates have changed as new boundaries have formed and old ones have shut down. A tectonic plate can split into two through a process called “rifting”. This has happened in many places across the world throughout geological time, and is happening right now in the East African Rift Valley. Here, the African plate is “unzipping” down it’s eastern side, splitting into two new plates. Hot material from the mantle is rising up from the under the crust, forcing it to split apart. (this process is explained nicely in this youtube video https://www.youtube.com/watch?v=Z9Hr7V1S0pI). As it splits, volcanoes erupts with the new hot magma that has forced its way up (google “East African Rift Volcanoes” and you will see there are a lot of them!) As the plates move apart, rift “basins” are formed- basically, valleys where new sediments and rocks will form. At the moment, the East African Rift Valley contains a series of these basins, some of which have lakes in them. These lakes are some of the oldest and deepest in the world. In the future, perhaps in millions of years, a new ocean may form where the East Africa Rift currently is, and “seafloor spreading” may take place. This is where the continents have completely separated due to rifting, and the magma being forced up forms oceanic crust in between the continents.