It might be impossible to predict when the next earthquake may occur but scientists can pin down what is called a recurrence interval or the average time span between earthquake occurrences.

For the West Valley Fault, four major earthquakes have been determined to have taken place in the last 1,400 years. It has a recurrence interval of 400 to 500 years. The last major earthquake originating from the fault was recorded in 1658 or 357 years ago.
This means that it may be time soon — perhaps in our lifetime, or that of our children — for another major movement in the fault.

According to the Metropolitan Manila Earthquake Impact Reduction Study (MMEIRS), a 7.2-magnitude earthquake from the West Valley Fault will result in the collapse of 170,000 residential houses and the death of 34,000 people. Another 114,000 individuals will be injured while 340,000 houses will be partly damaged.
At least seven bridges will fall off while 10 percent of public buildings will be heavily damaged.