^11:13 At that very hour there was a severe earthquake and a tenth of the city collapsed. Seven thousand people were killed in the earthquake, and the survivors were terrified and gave glory to the God of heaven.

At that very hour

Again, note the precision. It's "at that very hour" not "some time later". God's timing is always "on time".

• there was a severe earthquake and

  There is no mistaking that these are God's two witnesses (verse 4). The earth through a physical quake acknowledges their true standing.

• a tenth of the city collapsed.

  It was violent enough that buildings collapsed. It is not clear that the epicenter was where the two witnesses were whisked away into heaven or at the spiritual center of the city. Note that the veil of the temple (some distance from Golgotha) was torn in the earthquake that followed Christ's death on the cross, Matthew 27:51-56.

• Seven thousand people were killed in the earthquake,

  Some of these people may have been "big shots" from the political realm, the news media, and religious leaders. The world had kept a close watch on these two witnesses and their departure. And this is the price they will pay for rejoicing over the two witnesses' death (verse 10)!

• and the survivors were terrified and gave glory to the GOD OF HEAVEN.

  Those alive recognize God as the one who caused the earthquake. but note they only can give GLORY. The time for repentence is passed. When God performs a miracle such as this uptaking or a healing, it is not only an event for the ones taken up or healed, it most directly affects the onlookers including skeptics (Luke 5:17-26).

This concludes the "TWO WITNESSES" interlude.