| Vatnafjöll | |
| Elevation M: | 1235 |
| Location: | Iceland |
| Map: | Iceland |
| Coordinates: | 63.92°N -19.67°W |
| Type: | Fissure vents of Hekla |
| Age: | Tephrochronology |
| Last Eruption: | 1200 years ago |
Vatnafjöll (pronounced as /is/) is a 400NaN0 long, 90NaN0 wide basaltic fissure vent system that is south-east of Hekla, Iceland. It includes from the north towards the south the hills of Innri-Vatnafjöll at high, Fremri-Vatnafjöll at and Vatnafjallarani at as the main Vatnafjöll edifice,[1] at a distance of about from Hekla.[2] It is part of the same system as Hekla,[3] and the term Hekla-Vatnafjöll volcanic system has been used to describe it.[4] More than two dozen eruptions have occurred at Vatnafjöll during the Holocene Epoch. Vatnafjöll has not erupted during the last 1100 years.[5] While these eruptions were predominantly effusive some basaltic tephra deposits have been found up to away.[6]
A with an epicenter near the main Vatnafjöll edifice occurred on 25th May, 1987,[5] where the transform South Iceland seismic zone meets the East volcanic zone of Iceland. Later analysis has suggested that initiation was from strain relief but a subsurface dyke intrusion then occurred over the next 3 days.