The fault line along Chile's 4,200 kilometer long coast has constantly shifted during the last 140 years and there have been frequent earthquakes, but the area to the north and south of this week's quake hasn't had an earthquake in around 140 years and a large earthquake of 8.8-8.9 magnitude is expected sometime in the future, it could be tommorrow or it could be in 50 years, because scientists are still unable to predict earthquakes with accuracy.