Hi. You did not enter the text to which this question refers. This makes it impossible for this question to be answered. However, I will try to help you as best I can by showing you how to find this answer.
It is only possible to find the emotional appeals used in the text by reading the text. However, through the context of your question, we can see that the text relates moments when tragedies happened. Thus, we can consider that the author presents moments of suffering and despair, which stimulates the public's empathy and compassion in relation to what is being presented. These feelings will help the public to agree with the author's arguments in relation to these tragedies, which will encourage the public to prevent tragedies from occurring, to demand punishments from those responsible for the tragedies, among other attitudes supported by the author.
The common element among all the tragedies presented can only be perceived by reading the text. In this case, you must identify a similarity between the tragedies, or an element that repeats itself in all of them.