How do I find out how many years it will take? 


The San Andreas fault is a dextral (right-lateral) strike-slip fault that runs between Los Angeles and San Francisco. This means that Los Angeles is slowly approaching San Francisco. Assuming the average slip rate of 2.1 cm/year remains constant, in about how many years will Los Angeles be directly west of San Francisco? Los Angeles is presently 519 km from San Francisco. (Hint: 1 cm = 0.00001 km.)