I want to undestand why earthquake can't be predicted even very short time before it happens?

Because we can't measure the forces involved on the crust.

would you please explain a little further?

 

Why these forces can be measured?

What are the parameters that can be measured?

The main problem is that we know of nothing that happens before an earthquake that only happens before an earthquake, and always happens before an earthquake. We also can't predict the movement of the earth's crust exactly (it's a. much too complicated, and b. chaotic).

we know of nothing that happens before an earthquake that only happens before an earthquake, and always happens before an earthquake

 

but there is so much data collected before earthquake happen ....

so if calculations or simulations are too complex and chaotic to be done why then stastical methods don't work?

at least it could give us some time range...