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

Styles of Basaltic Eruption at Lakagígar


Two types of tephra are found today at Lakagígar, providing physical evidence of the styles of volcanism during the 1783-84 eruption. The two tephra types are classified by Thordarson and Self (1993) as strombolian and phreatomagmatic. The strombolian tephra is most common and is characterized by a glassy skin covering the surface of each clast (lapillus), indicating that it was still partially molten as it was falling. These lapilli in fact could be the products of either strombolian or hawaiian style volcanism. The phreatomagmatic tephra has no glassy skin and is entirely vesiculated, indicating that it was completely fragmented upon eruption.

Strombolian tephra.  Looks like a handful of coal.
Strombolian tephra with Pele’s hair from the third fissure eruption at Lakagígar on June 14, 1873.
Credit: Maryjo Brounce, 2008

Video: Eruption Animation (0:19)

Check Your Understanding

Question - Multiple Choice

What style of volcanism is shown in the movie above?


Click for answer.

This is an example of a strombolian eruption, characterized by short bursts of lava fountaining.