...causing a chain of reactions...(Para. 1)
The phrase "causing a chain of reactions, ranging from comfort to fear." is an adverbial of result, used to describe the result of "show our true feelings..."
"a chain of something" means a sequence of them happening one after another, for example,
a chain of events 一系列事件
a chain of accidents 一系列的意外事故
a chain of thoughts 一连串的想法
a chain of bad luck 一连串倒霉的事情