Courtsey of USGS
You learned that 25,000,000 years ago the East Pacific Rise first began to push the Cocos plate. The Cocos plate moves 4 to 9 cm. a year pushing the American plate. The 2 plates rub together so much that about every ten years there is a notable earthquake along the plate line. This is because one plate dives under the other providing an epicenter for an earthquake that may be devastating.
Geoscientists predicted that 5 earthquakes would hit Mexico between the years of 1978 and the end of the year 2000. Four of the five earthquakes have occurred. They predicted these earthquakes using the seismic gaps theory. This theory is based on how far apart the plates are, they then approximate how many years it will be before it releases pressure. Many predictions can be made but they are not precise because it's impossible to know exactly when and where an earthquake will strike. A notable earthquake was on April 18, 1906 in San Francisco. It measured as a 8.3 on the Richter Scale.
There was another earthquake in San Francisco in 1989. This was called the La Preita Earthquake.