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How does an asymmetrical rift valley form?

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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.

An asymmetrical rift valley forms through a process distinct from the simple, symmetrical graben model, where a block drops evenly between two major faults.12

Instead, an asymmetrical rift is characterized by one steep wall and one gentle side. The steep wall is created by displacement along one or two major faults. Conversely, the opposite side lacks a major bounding fault; instead, it is formed by the flexing of the lithosphere and the tilting of the surface.2

In these structures, the valley floor typically rotates about an axis, causing the most rapid sinking to occur along the side defined by the major fault. Notable examples of this asymmetrical formation include Death Valley, which features a steep eastern margin and a gentler western edge, and the Baikal Rift, which exhibits a steep northwestern edge and a more gradual southeastern slope.2