posted on Jun, 2 2006 @ 05:05 PM
Because it is not a perfect science yet. Humans are physically unable to set up seismic monitors on every single fault line and crack, scientists
have tried and there is an extensive monitoring system, however that only tells us when one happens and doesn't predict it. Also you have to keep in
mind that the way the plates moves causes predictable and unpredictable changes, some quakes trigger other quakes, while some happen in swarms on a
regular basis, there is also the possibility of human triggered quakes...(digging, mining, etc)
The reason people say a "major earthquake" might be coming is completely speculative based on various patterns that can be developed when monitoring
seismic readings. Some people look at water temps, others develop their own patterns from previous quakes, some look to signs from animals, etc.
Really there is too many variables I believe that play a part in earthquakes which prevents accurate predictions.