Voies de magma ascendant à l'intérieur des fissures verticales.

The interior of a typical large volcanic edifice is crossed by hundreds of dikes. Very often, dikes occur as swarms concentrated within zones of structural weakness within a volcanic edifice. This is nicely illustrated by the dikes exposed at the caldera cliffs of NE Santorini, where the interior structure of ancient stratovolcanoes (ca. 500-300 ka) of northern Santorini (Thera) is exposed (photos below). These dikes follow a structural trend of volcanism on Santorini (read more of Santorini's geology on the Santorini pages).