Sudoku Earthquake

In Sudoku Earthquake we take a normal 9 x 9 Sudoku puzzle and shake it up.

As you can see in the sample below there's a "fault line" - the seven reddish squares - stretching from one edge of the puzzle to another. The digits that appear along the fault line are listed below the puzzle.

In this sample you can see that there are a "3", two "4"s, two "6"s an "8" and a "9". What about "1", "2", "5" and "7"? Well, they don't appear anywhere along the fault.

  1     5     6 2
            2    
4             8  
            2    
        2   9   8
2   9 4          
    1     3      
        9   5   6
      6 8        

3 4 4 6 6 8 9
← (the fault line)

 

Solving Sudoku Earthquakes

To solve an Earthquake puzzle you'll want to move back and forth between the fault line and the normal puzzle. As the sample below shows, for a smaller fault you can often fill in several digits early on - but don't count on it. Keep your eyes open for digits being forced into a particular space, or being split between possibilities. Also remember that if a digit does not appear on the fault or all occurrences of that digit have already been placed, none of the remaining fault spaces will have that digit.

In the sample above, let's first look at the possible digits along the fault. Since there are two "4"s along the fault, it's easy to figure out where they go. Since they can't be in the same row, column or 3 x 3 box, one of the "4"s has to go into the middle of the center left box, forcing the other "4" to be at the bottom right edge of the fault.

  1     5     6 2
            2    
4             8  
            2    
  4     2   9   8
2   9 4          
    1     3      
        9   5   6
    4 6 8        

3  4   4  6 6 8 9
We also have two "6"s along the fault line. Since each of these must be in a different 3 x 3 grid one of them must appear in the top row of the lower left 3 x 3 grid, forcing the other "6" to be in the center left. Our single "9" is easy to place now, leaving just the "3" and "8" to be found.
  1     5     6 2
            2    
4             8  
            2    
6 4     2   9   8
2   9 4          
  6 1     3      
        9   5   6
  9 4 6 8        

3  4   4   6   6  8  9 

In the Sudoku Earthquake you'll find 101 Earthquake puzzles ranging from the milder tremors all the way up to earth-shatteringly difficult puzzles. As a bonus, we've also include a mix of new TrividokuStars & Stripes Sudoku and Sudoku Islands puzzles.

Title:
Earthquake
ISBN:
978-0-9815351-4-2
Item #
53514
Published:
2009
Pages:
142
MSRP:
9.95USD
Author:
Matt Mayfield