Sample Problems for Fault ID & Rock Deformation

1)     If the laws of physics could somehow be changed so that rock became more brittle under higher pressure, then which of the following would be true?

1. Earthquakes would only be able to occur within the Earth’s crust.
2. Earthquakes would only be able to occur within the Earth’s lithosphere.
3. There would be fewer earthquakes occurring than there are now.         
4. There would be less faulting of rocks occurring than there is now.
5. There would be less folding of rocks occurring than there is now.

2)     In the figure of the mountains shown below on the left (Image A), which of the following is true concerning the rock folds?

1. The folding is most likely an example of plastic deformation caused by convergence.
2. The folding is most likely an example of plastic deformation caused by divergence.
3. The folding is most likely an example of elastic deformation caused by convergence.
4. The folding is most likely an example of plastic deformation caused by shear.
5. The folding is most likely an example of brittle deformation caused by convergence.

A B

3)     In the picture above on the right (Image B), points A and B were originally touching but have been offset by a fault. What type of fault is this if the photograph was taken of a vertical surface of an outcrop running along the side of a highway?

1. The fault would be a reverse fault.                                
2. The fault would be a normal fault.                                 
3. The fault would be a thrust fault.                                  
4. The fault would be a right-lateral strike-slip fault.        
5. The fault would be a left-lateral strike-slip fault.          

4)     If all the faults in the area of Image B were similar to the one shown, then which of the following is most likely to be true?

1. The faulting would most likely have formed from compression along a transform plate boundary.
2. The faulting would most likely have formed from shear stress along a transform plate boundary.
3. The faulting would most likely have formed from tension in a convergent plate boundary.
4. The faulting would most likely have formed from compression in a convergent plate boundary.
5. The faulting would most likely have formed from tension in a divergent plate boundary.

                                                                                              
5)     If it turned out that the photographer’s notes were wrong and Image B was actually an image of the horizontal floor of a rock quarry, then which of the following would be true?

1. The fault would be a joint formed by release of pressure as the overlying rock was quarried away.   
2. The fault would be a normal fault formed by tensional stress.             
3. The fault would be a reverse fault formed by compressional stress.    
4. The fault would be a left-lateral strike-slip fault formed by shear stress.             
5. The fault would be a right-lateral strike-slip fault formed by shear stress.           

C.
6)     The picture at left (Image C), shows an areal view of a stream that has been offset by a fault. What type of fault is this?

1. A normal fault caused by tension.
2. A reverse fault caused by compression.
3. A right-lateral fault caused by shear.
4. A thrust fault caused by compression.
5. A left-lateral fault caused by shear.

7)     In the map shown below on the left (Image D), which of the following is true about the three faults shown.

1. The North Anatolian Fault was formed by a completely different type of stress than the East Anatolian Fault.
2. The Dead Sea Fault is caused by compression, while both the North and East Anatolian Faults were formed by tension.
3. Regardless of their sense of motion, all three faults shown formed from the same type of stress, namely shear.               
4. The North Anatolian Fault was caused by shear, while both the Dead Sea and East Anatolian Faults were formed by compression.
5. The Dead Sea Fault is caused by tension, while both the North and East Anatolian Faults were formed by compression.

D   E

8)     In Image E, shown above on the right, Fault B is which type of fault?

1. A reverse fault caused by compression.
2. A normal fault caused by tension.
3. A right-lateral fault caused by shear.
4. A left-lateral fault caused by shear.
5. You cannot determine this without more information.

9)     Which of the following is most likely to be true concerning the stresses that caused the three faults A, B & C shown in Image E, as well as the folded rock layers labeled D?

1. Faults B and C formed from the same type of stress, but Fault A formed from an entirely different type of stress than B or C.
2. The folding formed from compression, but all three faults formed from tension.
3. The folding formed from compression, but all three faults formed from shear.
4. All four features (all three faults and the folding) formed from the same type of stress, although not necessarily at the same time.
5. Fault A formed from one type of stress, Faults B and C from a second type and the folding D formed from a third type of stress.

10)   And finally one from the Old Testament: “And his feet shall stand in that day upon the Mount of Olives… and the Mount of Olives shall be cleaved in half, on the east and on the west, creating a great valley, and half of the mountain shall be moved to the north and half to the south. … in the days of Ozias, King of Juda.” Based just on this written description, which type of fault most likely runs through this area? (Hint: Realize that, in the writing style of the time, the passage is saying the east side moved north and the west side south.)

1. A left-lateral strike-slip fault.                                        
2. A right-lateral strike-slip fault.                                      
3. A normal fault.                                                               
4. A reverse fault.                                                              
5. A thrust fault.                                                                

It may help to draw this last one out.

Answers