There is more than one methodology in interpreting Revelations: the previous responder used "Jewish Apocalypse" as a methodology, but it 'presumes' all Jewish apocalypse ended in the 1st century; a view that is 'backward looking' and doesn't take into account the next 19+ centuries.
There is a "pattern of judgments":
1) The Seals are Broken (Chapters 6-8) These are the 1st indicators of God's Judgment on the earth. The Lamb w/7 Horns and 7 Eyes (The Risen Christ-Rev. 5:6) has the authority to release them. These are the "1/4" judgments (Rev. 6:8),"
And power was given unto them over the fourth part of the earth, to
kill with sword, and with hunger, and with death, and with the beasts
of the earth.
There are numerous interpretations as regarding these judgments; from a Historicist View, they are progressive throughout history. If you understand the color "white" to represent "righteousness" and "purity", the 1st judgment is the rider of the white horse. He isn't Christ-that doesn't come until Chapter 20, but his "horse" or "vehicle" is one of purity. This judgment can be most accurately represented by Constantine's vision, who was told "In hoc signo vinces"(under this sign, conquer) and the 'sign' was the sign of the cross. This is NOT to say that Constantine, or any subsequent nations that were "conquered, then Christianized" were 'righteous' , but we have seen this pattern throughout history. Even William McKinley, who after promising independence to the Philippines, said, "Do I free them, or Christianized them?" The result was a war for independence that got crushed, with many more casualties than the Spanish-American War. And it brought in an enormous influx of Protestant missionaries, who's legacy can be seen in the remote areas of the Philippines today. This same action, called "Colonialism" was in every country of the world. The rider of the White Horse wears a 'crown', which is a sign of authority, and government.
1/4 of Europe was decimated by the Black Plague, an indication of the rider of the 4th Horse(Pale).
The next set of Judgments are the angelic trumpeters-who sound a "warning" as judgment is being poured out. These are the "1/3rd" judgments as "
the third part of trees was burnt up'
the third part of the sea became blood
And the third part of the creatures which were in the sea, and had
life, died; and the third part of the ships were destroyed
a great star from heaven, burning as it were a lamp, and it fell upon
the third part of the rivers, and upon the fountains of waters;
the third part of the sun was smitten, and the third part of the moon,
and the third part of the stars; so as the third part of them was
darkened, and the day shone not for a third part of it, and the night
These judgments have also for the most part happened: Famine has gripped a third part of the world; the 1/3 part of trees is well documented, not by harvesting them but by parasites. I watched as all our "stately" elm trees vanished, to be replaced with "ash trees" which are succumbing to the emerald borer. This is happening all over the world-not all at once, but dramatically.
So judgment increases progressively, until we get to Chapter 16. What we see up to this point, is judgments upon the earth for not embracing the Gospel, as the vials(bowls) are poured out, we see the final wrath of God for not only "rejecting" the true Gospel, but embracing a "False Gospel", of the Antichrist and False Prophet.
These have not been fulfilled yet; many say it is during Daniel's Final Week(explanation by Dwight Pentecost), and I tend to agree with them. Your question about the 2 "vial" judgments must be dealt with separately, as Vial "4" and Vial "5" are 2 separate vials. You seem to be 'lumping them together' when in fact they are 2 separate events, and distinguishing signs for each.
All judgments are the work of God, not the work of man. "Pharaoh's magicians who imitated the 1st 2 miracles of Moses cannot be counted amongst the 10 plagues(Ex.8:18; though what they did merely increased the suffering of their people. It is the "finger of God" which causes these 'vials'. The 5th "vial" is poured out on the "seat of the Beast". Since the "Beast" is figurative, his "seat" is figurative, and "darkness" is not physical darkness but intense evil. Therefore, to discuss a literal "gamma ray" burst as a "figurative" interpretation fails the test of keeping "literal" and "figurative" separate. God doesn't 'mix His metaphors'. and neither should we.
As to a "gamma ray" burst causing earth to heat up and "scorch" it's inhabitants; it's possible. The 4th vial "scorches mankind" and while one could attempt to conjure a 'figurative' meaning for scorch, the literal one in this verse is the one we must go to, since there are no other 'qualifiers' that make it figurative. The important consideration is that it is the finger of God, not man.
In summary, exegetically the 5th Vial judgment cannot be seen as a "gamma ray" burst, the 4th one could. One must be very careful in applying empirical data to the works of God, as the Bible is not a book of science, it is a book of Truth, and "facts" and Truths are 2 different things.