In viewing this opening sequence, why do u believe the Parisian audience rioted during the premiere in 1913

This question seems to be incomplete. However, there´s enough information to find the right answer.

The Rite Of Spring, premiered in 1913 at Le Sacre Du Printemps in Paris, had an unexpected composition and choreography that was most likely the reason for the riot that ensued that day.

Explanation:

Igor Stravinsky developed this composition based on Russian folk tradition, rejecting the usual tonality, metre, rhythm, stress, and dissonance of music in that period. Furthermore, the dance choreographed by Nijinsky, full of sharp and irregular movements that don´t seem like the traditional movements of ballet, must have been shocking at the time.