the word 'upsurge' is a modern english compound formed from two pre-existing english elements. the first element, 'up', is a native english adverb and preposition of germanic origin, ultimately from proto-indo-european upo, meaning 'up from below'. the second element, 'surge', entered english from old french 'sourdre' (to rise, spring up), which itself derives from latin 'surgere', a contraction of 'subrigere' (to rise, lift up), from 'sub-' (up from below) and 'regere' (to keep straight, guide). the literal combination of 'upward' and 'rise' creates a tautological or emphatic compound, logically intensifying the sense of a sudden, powerful increase or upward movement, which perfectly captures its modern abstract meanings related to sharp rises in activity, emotion, or quantity.

Structure: up (upward) + surge (rise) up (old english, adverbial particle denoting upward direction or increase); surge (latin via old french, meaning to rise)