Analysis of A.D. 19—?

AS in some quiet city bathed in sleep,
 Where like a kiss the twilight lingereth,
 When suddenly the earth stirs far beneath—
 Just moves, then pauses—and a silence deep
 Falls on all ere the second shock should sweep
 Spire, column, pinnacle to shapeless death!
 And white face peers at white face, and no breath
 Is drawn, and every heart forgets to leap!  
  So now across this quiet, dreaming world
 The first faint shock has thrilled; and men, aghast,
 Wait for the second, whose blind forces pent
 Shall in one last convulsion find their vent;
 And all the builded fabrics of the past
 Shall be in ruins on their builders hurled.