The Sound of the Earthquake - the Voice of the Earth

"V'Chol Yisroel Asher Sevivoteihem Nasu L'Kolam" - all of Bnei Yisroel that were around them ran from the voice [Korach 16:34]. Which voices were they running from? The Mizrachi says it could not have been from the screaming of the people falling into the open earth or else all the people would run towards the voices to see this strange event, and not away from it. Instead he says it was from the booming noise of the earth opening up. 

The Tosfos Yom Tov says that the voice was that of the earth speaking and announcing that the sinners were swallowed alive and still living inside the bowels of the earth. He brings proof from the pasuk that says [Korach 16:30], "U'Phatzta HaAdama Et Piha" the earth opened its mouth. The word Phatzta implies that it opened its mouth to speak because the word that is used in this parsha to describe the opening of the ground is "VaTiftach HaAretz Et Piha". 

Maybe this would explain the mishna in Pirkei Avos [5:8] that says that one of the ten things created Erev Shabbos Bein HaShmashos was "Pi HaAretz" - the mouth of the earth that swallowed Korach. if it meant the crack in the earth then why would this be a special creation? The earth splitting was not a one time event and happens from time to time. Moreover, a crack is not a creation. Maybe it means the mouth of the earth that spoke, similar to another creation in this mishna, the mouth of the donkey of Bilam who spoke.