What causes ocean floors to expand?

Answer 1

Ocean floors expand primarily due to the process of seafloor spreading, which occurs at mid-ocean ridges where tectonic plates diverge. As magma rises from the mantle, it solidifies at the surface, creating new oceanic crust. This process is driven by mantle convection, where heat from the Earth's core causes the mantle to flow, pushing the plates apart. Additionally, volcanic activity and tectonic movements contribute to the expansion of the ocean floor.