Pacific and asian plates. One of them was the Pacific Plate, the largest of all modern plates at million square kilometers.
Eventually Africa will split apart.
The magma, which is lighter than the surrounding mantle material, rises through the mantle and the overlying oceanic crust to the ocean floor where it creates a chain of volcanic islands known as an island arc.
To the south a number of smaller tectonic plates are in collision with the Pacific plate from the Mariana Islands, the Philippines, Bougainville, Tonga, and New Zealand.
Many strong megathrust earthquakes occurred here, some of them among the largest on world record, including the Kamchatka earthquakes of estimated M9.
During the same period, the Atlantic Ocean began to open up between northern Africa and North America, and India broke away from Antarctica.
A geological map of the seabed of the Pacific Ocean uncovers geologic sequences over millions of years, and house information that they formed the Ring of Fire on the perimeters of the largest ocean.
However, the lithosphere is not as rigid as we would like to think.