Why are aftershocks more dangerous than mainshock?

Related questions

1. How many aftershocks are normal?
2. Can a person feel an earthquake before it happens?
3. Does the ground split during an earthquake?
4. Why are aftershocks so dangerous?
5. How long does a 7.0 earthquake last?
6. What should people do after an earthquake?
7. How strong is a 9.0 earthquake?
8. What was the deadliest earthquake?
9. What would a 7.0 earthquake feel like?
10. How far away can you feel a 7.0 earthquake?

Tags

1. #shock
2. #because
3. #damaged
4. #magnitude
5. #collapse
6. #dangerous
7. #unpredictable
8. #usually
9. #aftershocks
10. #buildings
11. #large