How does the spreading rate affect the width of an oceanic ridge?

The width of an oceanic ridge is fundamentally determined by the thermal contraction of the oceanic crust and upper mantle as they move away from the spreading centre. Because this cooling process occurs over a specific timeframe—typically reaching a steady thermal state within 70 to 80 million years—the rate at which the seafloor spreads directly influences the ridge's dimensions.1

Specifically, faster-spreading ridges, such as the East Pacific Rise, are wider than slow-spreading ridges, like the Mid-Atlantic Ridge. This occurs because, at higher spreading rates, the crust is carried further from the ridge crest before it has the opportunity to cool and contract to its steady-state depth. Conversely, at slower rates, the crust reaches this cooled, deeper state closer to the crest, resulting in a narrower ridge profile.1