Take a good look at the map and study well the presence of mining sites and the locations where the dead deep-sea animals were found. This may help you find the answer.
Unknown to most of us, Phivolcs recorded that almost every day there are big tremors occurring in Surigao after the February 10 magnitude 6.7 earthquake but were no longer reported in the mainstream news media. If you are interested, you can openly view the recorded seismic events online. See the Phivolcs official daily updates of seismic activity in the country HERE.