Earthquake Safety Action Puzzle

GIF B&W image of earthquake crack

                   
                   
                   
                   
                   
                   
 
      E R          
    A R T   A N    
  H A H O   D H O  
C W V R E L N T O  
S O G K N U T D E  
S T H E O S D R D P

Using the letters below the puzzle box, fill in the earthquake safety action message beginning with "When"