The intersection of the main fault systems (NW-SE to WNW-ESE and NNW-SSE to NS) with former and deep east-west oceanic crust faults determines the location of S. Miguel central volcanoes, while on the rift zones, the monogenetic cones lie mainly on the NW-SE to WNW-ESE-trending structures. At Sete Cidades central volcano, the faults have a dominant NW-SE trend, displayed on the northwest flank of the volcano by the Mosteiros Graben, while the conjugated system has a N-S trend, with a major fault probably controlling the north-south-trending alignment of the eruptive centres in the caldera. The important NW-SE fracture zone crosses the Sete Cidades volcano and extends southeast to the Picos rift zone where it is manifested by dextral en échelon alignments of monogenetic cones, defining two main volcanic ridges. At Fogo volcano, the dominant faults trend NW-SE to NNW-SSE, being particularly evident on the north flank, where volcanic alignments, extending from the north coast to the summit area, border a subsided area defining the Ribeira Grande Graben. This structure probably controlled the present shape of the summit caldera.

At the eastern part of S. Miguel Island, the main tectonic structures trend WNW-ESE and are represented by volcanic alignments at Congro rift zone, crossing Furnas central volcano. The Furnas volcano is affected by fault systems trending WNW-ESE, NE-SW, N-S and NNW-SSE, expressed by volcanic alignments, linear valleys, and caldera outlines. The orientation of the volcano calderas’ walls coincides with the main fault trends (WNW-ESE and NE-SW), suggesting that caldera collapses were controlled by structural weaknesses.​