Godzilla shakes city

But just then, a sound like a tremendous hammer hitting a door echoed over the city, shaking the foundation of the building they occupied.  The booming sound repeated two more times.  Each blow was so intense that it vibrated the floor under them.  Surprised, Zoe Kemmering stepped backward until her spine pressed against the crystal wall behind which the Ancient Ones waited motionlessly.
…
Outside the edge of the city, the booming, pounding noise continued during the firefight.  Finally, a crack appeared on the massive crystal iris at the entrance to the city.  Then another appeared.  Soon, these two cracks joined.
Finally, with an ear-shattering crash of tumbling crystal shards, the wall exploded inward.  As thousands of tons of gushing water rushed into the necropolis from the underground lake on the other side of the iris, Godzilla stumbled through the opening he’d made and into the city of the Ancient Ones.