You will discover that all of the Erazo's in Bayamon, PR. are related. My mother's name is Erazo (daughter of Carmelo Erazo and Eusebia Cruz) and she tells me that most the Erazos' were women, so the name died out after a generation. Since the last name was only passed on by a few baby boys, most of the Erazo's end up being related.
Good luck in your search. You should look up the name in the Bayamon phone book; it's not as extinct as we might think it is.