Aniakchak reported activity

Event Name : Aniakchak Vent Mountain Tephra

Start: 840 (± 30 Years)	Years BP Tephrochronology
Stop: 570 (± 40 Years)	Years BP Tephrochronology

Tephrafall:

Description: From Bacon and others (2014): "Vent Mountain scoria and spatter cone is the most prominent topographic feature within the caldera (figs. 10, 12C and 12D [in original text]). The cone rises 440-530 m above the caldera floor to an elevation of 3,350 ft (1,021 m). The 210-m-deep summit crater has a diameter of ~800 m. Numerous blocky lava flows emanate from the cone's lower flanks and from a prominent fissure vent that cuts the southwest flank. Although some outcrops of basaltic andesite and mafic andesite lava west of The Gates and in the larger maar crater possibly had source vents now hidden beneath Vent Mountain, the majority of products attributed to that volcano are silicic andesite and dacite."

"Tephra compositionally similar to Vent Mountain lava is stratigraphically above Half Cone lower light pumice (weighted mean age 840+/-30 yr B.P., table 1 [in original text]) and below Half Cone upper light pumice (weighted mean age 570+/-40 yr B.P., table 1 [in original text]) in a section 6 km east-southeast of the caldera (table 2 [in original text])."