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How does a graben become 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.

A graben is essentially a geological term for a depressed segment of the Earth's crust, often described as a ditch or trough, that is bounded by faults on at least two sides. The terms are closely related because a rift valley is a type of tectonic depression formed by this process.123

A graben becomes a rift valley through the extension of the Earth’s crust. As large crustal blocks or lithospheric plates diverge, the brittle crust fractures, allowing a smaller block to slide down into the resulting gap. This down-dropping of a crustal block between surrounding fault blocks creates the characteristic steep-sided, flat-floored landform known as a rift valley.14

While a simple graben is defined by its structural depression, the term rift valley is often used to describe these larger-scale tectonic features, which can span thousands of kilometers in length. Some rift valleys may also incorporate more complex features, such as horsts or volcanic activity, depending on the specific tectonic forces involved.134