Final answer:
Nicholas II's abdication led to the establishment of a provisional government in Russia.
Step-by-step explanation:
The event that caused the Duma to establish a provisional government in Russia was Nicholas II's abdication. Nicholas II, the last Tsar of Russia, abdicated the throne on March 2, 1917, following widespread protests and demonstrations by the Russian people. This led to the formation of a provisional government, which aimed to transition Russia towards a democratic system.
Learn more about Russian history during World War I