Volcanism is also part of some very complex features on Venus.
They differ from volcanoes in two ways. First, volcanoes often form on older rifts or faults, but they do not cause this faulting. Second, most volcanoes are just large piles of lava. In contrast, the tectono-volcanic structures are thought to form by faulting over rising magmas. Also, lavas make up only a small part of these structures.