Complex sentence: The population collapse of Tohoku, which began before the year 2000, has accelerated, now includes previously dynamic Miyagi, despite this, Sendai city has added population quicker due to the disaster.
Split into simpler sentences: The population collapse of Tohoku, which began before the year 2000, has accelerated, now including previously dynamic Miyagi. Despite this, Sendai city has added population quicker due to the disaster.