EMSC 100
Freshman Seminar in the College of Earth and Mineral Sciences

Events of August 1783 - February 1784 (Northeast Fissures)


Eruptive activity northeast of Laki mountain commenced on July 29, 1783, marked by explosive phreatomagmatic activity. The phreatomagmatic eruption lasted 2-3 days, producing a second tuff cone. Lava flowed both to the south and to the north, ultimately entering the Hverfisfljót River Gorge to form a second flow channel that would drain the lavas produced by the northeast fissures. The lava flow rate reached a maximum of 4 km/day between August 3-7, continuing at a lower rate until the next surge on September 1 (preceded by an earthquake swarm on August 23). Another earthquake swarm on September 26 was accompanied by intense volcanic activity, and both the Skaftá and Hverfisfljót rivers dried up during this time. Another fissure opened October 24-29, delivering a final surge of lava to the Hverfisfljót River Gorge. Effusive eruption continued at a diminished rate until February 7, 1874.

Fissure Eruption at Mauna Loa and a person standing to the left in front of the volcano.
This image of a fissure eruption at Mauna Loa in 1984 gives us a sense of what the Hawaiian-style stages of the Laki fissure eruption might have looked like. Note the human for scale in the lower left hand corner.
Credit: J.D. Griggs, U.S. Geological Survey.
Row of craters, northeast crater row at Lakagígar
Segment of the northeast crater row at Lakagígar as it appears today. This linear row of volcanic craters probably formed during a fissure eruption similar to the one pictured above.
Credit: Maryjo Brounce, 2008

Video: Fissure eruption at Eyjafjallajokull, Iceland, in 2010 (0:47)