It's a bit poorly worded, that is, it's redundant. I would say "risk = probability × consequences"

Interesting. I see the sentence is from a Korean publisher's source that tweaked final exam's sentence. The participial phrase seems to be modifying the preceding clause, so there should be a comma before "multiplied by..." as follows: The risk of a particular event is defined as the product of the probability of that event’s occurring, multiplied by the consequences should it actually occur. I don't think the sentence sounds natural even with the comma. It's just my opinion. I'm not a native speaker of English, so let's wait for further answers.