https://phys.org/news/2018-11-sunset-crater-san-francisco-volcanic.html

The eruption developed in three distinct phases: an initial fissure phase, followed by a highly explosive phase, and a final low explosive waning phase. The first phase was characterized by the opening of a 10-km-long fissure, which produced spatter mounds (Gyp Crater), a lava flow effused from the southwest end of the fissure (Vent 512 flow), and a 0.01 cubic kilometer dense rock equivalent (DRE) of pyroclastic fall deposit (Unit 1).

During the second highly explosive phase, the activity migrated to the northwest to evolve into a single-vent eruption, which formed the main scoria cone. The central vent activity was initially characterized by variable eruptive styles, which started the process of cone building, deposited a second pyroclastic layer (Unit 2; 0.01 square kilometers DRE), and started the effusion of the two main lava flows (Bonito and Kana'a).