Earthquake questions

1) Post your answers to these questions: What causes earthquakes? Of the following factors, which do you think is the most reliable predictor of earthquakes? Explain your answer please.

(a) recurrence interval
(b) animal behavior
(c) rock precursors

2) Post your answer to this question: Compare the use of the Mercalli scale and the Richter scale to measure the size of an earthquake. What are the advantages and disadvantages of using each scale?