At a mid-ocean ridge, the tectonic plates are moving away from each other; this is a divergent plate boundary where the plates pull apart and new ocean crust forms between them.

Plate motion at mid-ocean ridges

  • Mid-ocean ridges mark places where two oceanic plates diverge, meaning they move apart horizontally on either side of the ridge axis.
  • As the plates separate, magma rises from the mantle, fills the gap, and solidifies to create new oceanic crust, a process called seafloor spreading.

What ā€œmoving apartā€ looks like

  • If you stood on one plate at the ridge, the opposite plate would slowly move away from you, typically a few centimeters per year, like fingernail growth speed.
  • The ridge itself stays roughly centered between the diverging plates, continually producing new crust that pushes older crust farther away on both sides.

Why the plates move this way

  • Heat and upwelling in the mantle beneath the ridge help push the plates apart by creating buoyant, hot, and slightly elevated crust at the ridge crest.
  • Gravitational forces on cooling, denser oceanic plates (ridge push and slab pull) also contribute to the outward motion away from the ridge over millions of years.

TL;DR: At the mid-ocean ridge, the plates are divergingā€”moving apart from each other while new seafloor forms between them.

Information gathered from public forums or data available on the internet and portrayed here.