The Wikipedia article on Zeus tells us (emphasis mine):
Although etymology indicates that Zeus was originally a sky god, many Greek cities honored a local Zeus who lived underground. Athenians and Sicilians honored Zeus Meilichios ("kindly" or "honeyed") while other cities had Zeus Chthonios ("earthy"), Zeus Katachthonios ("under-the-earth") and Zeus Plousios ("wealth-bringing"). These deities might be represented as snakes or in human form in visual art, or, for emphasis as both together in one image. They also received offerings of black animal victims sacrificed into sunken pits, as did chthonic deities like Persephone and Demeter, and also the heroes at their tombs. Olympian gods, by contrast, usually received white victims sacrificed upon raised altars.
Which cities had a Zeus Chthonios or a Zeus Katachthonios cult? Did these cults consider Zeus a sky god with chthonic properties, or a completely chthonic deity?