Defined as a sag-caldera, Sachs is an elliptical depression 130 meters (81 feet) in depth, spanning 40 kilometers (25 mi) in width along its longest axis.

The morphology implies that a chamber of molten material drained and collapsed, forming a depression surrounded by concentric scarps spaced 2 to 5 kilometres (1.2 to 3.1 mi) apart.

The arc-shaped set of scarps, extending out to the north from the prominent ellipse, is evidence for a separate episode of withdrawal; the small lobe-shaped extension to the southwest may represent an additional event.

Solidified lava flows 10 to 25 kilometres (6.2 to 15.5 mi) long give the caldera its flower-like appearance.

Much of the lava, which was evacuated from the chamber, probably traveled to other locations underground, while some of it may have surfaced further south.