Numerous chiastic structures have been suggested for the book of Revelation. The structure presented here focuses the chiasm in 11:15-19. A strength of the structure suggested in the outline below is that identifies a "center" for the book according to the natural progression of the book. Several authors have observed the natural division between chapters 11 and 12. The end of chapter 11, concluding the seventh trumpet and the seventh seal, would be an appropriate conclusion to a book had not John received a second scroll with the admonition to prophesy again.
Another strength of the structure here is that is honors the clear parallel between the trumpets and the plagues (bowls of wrath). This is possible and logical when one considers that the seals of chapters 6 and the personages of chapter 12-13 both represent historical sequences. When the seals/trumpets and the personages/plagues are seen as units, the obvious parallels fall into place.
A 1:1-9 Prologue B 1:10-3 Initial vision: Christ among the persecuted church C 4-5 Heavenly Scene D 6 Historical-6 seals 1-2-3-4-5-6 7 Interlude: sealing of 144000, Great Multitude 8-9 7th seal = trumpets 1-2-3-4-5-6 10-11 Interlude: angel with second scroll, two witnesses E 11:15-19 7th trumpet: Kingdom Victory D'12-13 Historical-6 personages 14 Interlude: 144000, 6 angels and harvest of earth 15-16 7th personage = plagues 1-2-3-4-5-6 16: Interlude: 3 frogs gather for battle 17-18 7th plague = destruction of Babylon C' 19-20 Heavenly Scene (with 7 visions, "I saw") B' 21-22 Concluding vision: Christ among the victorious church A' 22 Epilogue