The volcanic zone of Iceland can be divided into several volcanic systems.  Each system typically
has a central volcano with a magma chamber underneath and a caldera in the middle.  A swarm of fissures
usually cuts the central volcano and extends 50-100 km in both directions along the volcanic zone.
The Krafla volcanic system is indicated with purple colour. (Map from Einarsson 1991, slightly modified).

Recent earthquakes

References:
Einarsson, P. 1991. Earthquakes and present-day tectonism in Iceland.  Tectonophysics 189: 261-279.

Einarsson, P. & K. Sæmundsson 1987.  Earthquake epicenters 1982-1985 and volcanic systems in Iceland.  In: Th. Sigfússon (ed.): Í hlutarins eðli: Festschrift for Þorbjörn Sigurgeirsson.  Menningarsjóður, Reykjavík (map).