Not all locations have central volcanoes: the Reykjanes peninsula, for instance, can erupt anywhere and does not revisit an old cone (other than in different episodes in the same eruption). Eruptions in different volcanic centres are mostly independent events, but as the eruptions can last for years to decades (such as in the Krafla fires – this can be seen as a single eruption or a series of related eruptions), two different systems may still erupt at the same time, largely by coincidence. There is a central volcano, 1km high, which has had rhyolitic eruptions, but it has had only a few eruptions since the ice age.