Hurricane is related to Tropical. Tropical is related to Palm. 
the last thing you do when you Buy is Pay. Pay is related to Cost. Cost is related to Estimate. Assess is a type of Estimate. 
Hurricane <--RelatedTo--> Tropical <--RelatedTo--> Palm 
Buy --HasLastSubevent--> Pay <--RelatedTo--> Cost <--RelatedTo--> Estimate <--IsA-- Assess 