According to Edski:
Discussion of the location of hell is not a hot topic these days. Most educated Christians have abandoned offering even the slightest defense of hell's classic locale (beneath the earth)...So it appears that after more than two thousand years, a majority of religious believers have chosen to reinterpret the Bible, in effect, to correct its authors, as well as theologians and evangelists of the past, without of course rewriting the Bible, except in their own minds.
So theologians before the advent of modern geology couldn't ask common sense questions about the logistics of hell. Let's see about that, shall we?
Here arises the question: If the fire is not to be immaterial, analogous to the pain of the soul, but material, burning by contact, so that bodies may be tormented in it, how can evil spirits be punished in it?...I would indeed say that these spirits will burn without any body of their own, as that rich man was burning in hell when he exclaimed, “I am tormented in this flame,” Luke xvi. 24. were I not aware that it is aptly said in reply, that that flame was of the same nature as the eyes he raised and fixed on Lazarus, as the tongue on which he entreated that a little cooling water might be dropped, or as the finger of Lazarus, with which he asked that this might be done,—all of which took place where souls exist without bodies. Thus, therefore, both that flame in which he burned and that drop he begged were immaterial, and resembled the visions of sleepers or persons in an ecstasy, to whom immaterial objects appear in a bodily form. For the man himself who is in such a state, though it be in spirit only, not in body, yet sees himself so like to his own body that he cannot discern any difference whatever.
Augustine, City of God
Whether the fire in which the wicked are to be tormented in soul as well as in body will be material and corporeal is controverted. The Romanists…do not hesitate to assert this…But others far more truly deny it and wish it to be explained metaphorically or allegorically…Because it is treated of the fire prepared for the Devil and his angels. And yet body cannot act upon a spirit, since it cannot act without contact wither mediate or immediate, which does not fall upon a spirit.
The various other phrases by which infernal punishments are described are to be understood not so much properly as allegorically, when they are expressed by “outer darkness,” “the worm,” “gnashing of teeth,” “chains of darkness,” “lake of brimstone,” “prison,” and “gulf,” and by other things of the same kind…For the same reason a metaphorical, not a proper fire is to be understood.
If heavenly goods are depicted under symbols of the most delightful things (which are to be understood not properly, but mystically and figuratively; as when mention is made of Abraham’s bosom, lying down in the kingdom of heaven with the patriarchs, of paradise, the tree of life, treasures, crowns and the like), why should we not think that the Holy Spirit employed equally figurative terms in the description of the opposite evils, so that the most direful torments are adumbrated by fire, which is wont to create the most intense pain?
Francis Turretin, Institutes, 3: 605-06.
Of course, the real reason that Turretin chose to “reinterpret” Biblical imagery is because he had access to 17th century 3D subsurface imaging technology. After mapping the interior of the earth, he discovered, much to his dismay, that hell was nowhere to be found in the nether regions of the earth. For his part, Augustine used P-waves and S-waves to model the interior of the earth. No fallen angels were detected!