The second one is push factors, the first one is pull factor, the fourth one is forced migration, and the third one is chain migration, hope this helps.
The long term result would be that the region where it has occurred will split and the two parts will move away from each other, the growing gap between them will be filled with water which in time will become sea, there will be significant climate changes, the one part that'll be moving into more isolated position will make life forms on it to evolve in a specific way and they will become very unique in time.
Overpopulation is a phenomena in which population of a concerned region raises explicitly in large numbers. The two main reasons for overpopulation in India are higher birth rate and lower death rate. India is facing many consequences due to overpopulation like unemployment, poverty, food insecurity, extinction of plant and animal species, loss of ecosystems, deforestation, water and air pollution and others.
