, ▁including ▁earth qu akes ▁and ▁steam ▁em issions . ▁▁ 1 8 1 5 ▁er u ption ▁ ▁Chron ology ▁of ▁the ▁er u ption ▁▁ ▁Before ▁ 1 8 1 5 , ▁Mount ▁Tamb ora ▁was ▁d orm ant ▁for ▁several ▁centuries ▁as ▁hyd r ous ▁mag ma ▁co o led ▁gradually ▁in ▁a ▁closed ▁mag ma ▁chamber . ▁Inside ▁the ▁chamber , ▁at ▁depth s ▁of ▁, ▁cool ing ▁and ▁partial ▁cry st all ization ▁of ▁the ▁mag ma ▁ex sol ved ▁high - press ure ▁mag m atic ▁fluid . ▁Over press ure ▁of ▁the ▁chamber ▁of ▁about ▁ ▁was ▁generated ▁as ▁temper atures ▁r anged ▁from ▁. ▁In ▁ 1 8 1 2 , ▁the ▁cr ater ▁began ▁to ▁r umble ▁and ▁generated ▁a ▁dark ▁cloud . ▁ ▁A ▁moder ate - s ized ▁er u ption ▁on ▁ 5 ▁April ▁ 1 8 1 5 ▁was ▁followed ▁by ▁th under ous ▁det on ation ▁sounds ▁that ▁could ▁be ▁heard ▁in ▁Mak ass ar ▁on ▁Sul aw esi , ▁at ▁a ▁distance ▁of ▁, ▁Bat avia ▁( now ▁Jak arta ) ▁on ▁Java , ▁ ▁away , ▁and ▁T ern ate ▁on ▁the ▁Mol u cca ▁Islands ▁at ▁ ▁from ▁Mount ▁Tamb ora . ▁What ▁was ▁first ▁thought ▁to ▁be ▁the ▁sound ▁of ▁firing ▁guns ▁was ▁heard ▁on ▁ 1 0 ▁and ▁ 1 1 ▁April ▁on ▁Sum atra ▁island ▁( more ▁than ▁ ▁away ). ▁On ▁the ▁morning ▁of ▁ 6 ▁April ▁ 1 8 1 5