Why are shallow earthquakes common along oceanic ridges?

Shallow earthquakes are common along oceanic ridges primarily because these regions are active divergent plate boundaries where the oceanic crust is under constant tension.123

The occurrence of these earthquakes is driven by several geological factors:

• Crustal Rifting: As magma wells up from the mantle to create new lithosphere, the crust at the ridge crest repeatedly rifts, heals, and rifts again. This brittle deformation of the shallow crust generates frequent seismic activity.13
• Transform Faults: Many earthquakes occur along transform faults—strike-slip faults that offset ridge segments. These faults are seismically active zones where tectonic plates slide horizontally past one another.423
• Depth Limitations: Earthquakes in these areas are restricted to the shallow crust because the high heat flow from the underlying mantle makes deeper rocks too ductile to store the elastic strain necessary to produce earthquakes.1

In contrast to subduction zones, where deep-focus earthquakes occur as lithospheric slabs descend into the Earth's interior, the seismic activity at oceanic ridges is confined to the shallow, brittle layers of the crust.12