Final answer:
Seafloor spreading is driven by the movement of tectonic plates and occurs at an average rate of 4 to 5 centimeters per year, with convection currents in the Earth's mantle facilitating the process.
Step-by-step explanation:
The process of seafloor spreading is driven by plate tectonics, and it occurs at an average rate of about 4 to 5 centimeters per year.
Seafloor spreading is a geological process where new oceanic crust is formed at mid-ocean ridges and slowly moves away from them. This occurs because of the movement of tectonic plates, which are large segments of the Earth’s crust and upper mantle. At the boundary of these plates, magma rises from beneath the Earth's surface to fill the gap created by the plates moving apart. As the magma cools, it forms new crust on the floor of the ocean. The motion of tectonic plates themselves is caused by the convection currents within the Earth's mantle, acting somewhat like a conveyor belt.
This mantle activity is how Earth dissipates internal heat, effectively acting as a cooling system for the planet. The average rates of seafloor spreading vary, with some places spreading faster than others, but on average, the rate is about 4 to 5 centimeters per year, which accounts for the constant renewal of the oceanic crust. This dynamic is a crucial aspect of the plate tectonics theory, which is fundamental to our understanding of geological phenomena such as earthquakes, volcanic eruptions, and the creation of mountain ranges.