20260610 13492100 1.0 TRUE Grímsvötn fissure swarm - Jóhannesson and Sæmundsson (1998a) Fissure swarm. Source: Jóhannesson, H. And K. Sæmundsson (1998). Geological map of Iceland: tectonics. Náttúrufræðistofnun Íslands, Reykjavík. Icelandic Institute of Natural History