3 0 5 0   BC ▁and ▁ 7 4 0   AD ▁ ± ▁ 1 5 0 ▁years . ▁An ▁earlier ▁cal der a ▁was ▁filled ▁with ▁la va ▁flows ▁starting ▁from ▁ 4 3 , 0 0 0 ▁years ▁B P ; ▁two ▁py ro cl astic ▁er u ptions ▁occurred ▁later ▁and ▁formed ▁the ▁Black ▁S ands ▁and ▁Brown ▁T uff ▁form ations , ▁the ▁last ▁of ▁which ▁was ▁emp la ced ▁between ▁about ▁ 3 8 9 0 ▁BC ▁and ▁ 8 0 0 ▁AD . ▁ ▁In ▁ 1 8 1 2 , ▁Mount ▁Tamb ora ▁became ▁highly ▁active , ▁with ▁its ▁maximum ▁er upt ive ▁intensity ▁occurr ing ▁in ▁April ▁ 1 8 1 5 . ▁The ▁magnitude ▁was ▁ 7 ▁on ▁the ▁Vol can ic ▁Ex pl os ivity ▁Index ▁( VE I ) ▁scale , ▁with ▁a ▁total ▁te ph ra ▁e ject a ▁volume ▁of ▁ 1 . 6   ×   1 0 1 1   c ub ic ▁metres . ▁Its ▁er upt ive ▁characteristics ▁included ▁central ▁vent ▁and ▁explos ive ▁er u ptions , ▁py ro cl astic ▁flows , ▁t sun am is ▁and ▁cal der a ▁collapse . ▁This ▁er u ption ▁had ▁a ▁long - term ▁effect ▁on ▁global ▁climate . ▁Vol can ic ▁activity ▁ceased ▁on ▁ 1 5 ▁July ▁ 1 8 1 5 . ▁Activity ▁res umed ▁in ▁August ▁ 1 8 1 9 — a ▁small ▁er u ption ▁with ▁" fl ames