How is modeling helpful to scientists?

Answer 1

Sometimes things underground are hard for us to see in 3D so we make computer models to show it.

Also, especially in geology, processes take a long long time. More than anyone's life time. So we use the data we have and the knowledge we hav to create computer simulations that can show us what will happen in a particular situation after many many years.

Answer 2

It helps us understand how things work. By changing conditions, we can get an idea of what are and are not important factors in governing how a process will progress, and often some very interesting and unexpected concepts arise out of the modelling work. Computer models allow scientists to look at large and complex systems that would not normally be easily tested in a bench scale environment.

Obviously the models are only approximations of the process or environment and thus are not strictly applicable to the real world, but interrelationships developed from the model can be tested against reality, and predictions can be made from these identified relationships once it is found to provide a reasonable estimation of the way the process works by comparison to real behavior.