Agarinagarao, as a responsible user of this site, I see the need to suggest correction for the benefit of the inquirer so he/she should give the proper and correct answer to his/her homework. And you responded with "edi wow"? I did not even post the correction below your answer. Fact is, if you really knew what PHIVOLCS is, you should have answered this question with correct abbreviation. Please don't be offended when someone offers suggestion or correction.