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How can hot material rising from the asthenosphere help form a rift valley?

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tectonic basins and rift valleys Escarpments of the Great Rift Valley rising above the plain north of Samburu Game Preserve, central Kenya. Beisa oryxes graze in the foreground.

Hot material rising from the asthenosphere contributes to the formation of a rift valley primarily through the processes of thermal uplift and crustal extension.12

When hot material upwells within the underlying asthenosphere, it exerts pressure on the overlying lithosphere, causing it to bulge upward. This process has two key effects:12
* Thermal Expansion: The heat from the rising material causes the lithosphere to expand, which contributes to the upward arching of the crust.1
* Stretching and Fracturing: As the lithosphere is pushed upward and bulges, it undergoes stretching. This tension causes the brittle crust to fracture and develop faults.12

As the plates diverge, these fractures are often invaded by ascending magma, which further pries the crustal blocks apart. The subsequent settling or "dropping" of these crustal blocks into the resulting gap creates the characteristic trough of a rift valley. This mechanism is frequently associated with extensive volcanism, as the rising hot material provides the source for volcanic activity along the rift axis.213