The reason why there are collisions between two continental plates is that the plates move. Although this movement is not visible to the naked eye, it registers on space-based geodetic measuring systems, according to Incorporated Research Institutions for Seismology (IRIS), a consortium of more than 100 U.S. universities. Geodesy is the science of the Earth's size and shape. When a moving continental plate touches another relatively stationary or moving continental plate, a collision occurs.
According to the Plate Tectonics website, the plates move because of forces deep within the radioactive core of the Earth. Softer rock lying below the plates, called the athenosphere, is subject to high temperature and great pressure. This keeps it in a semi-plastic state. The science behind all of this is still revealing amazing information. In essence, the athenosphere acts almost like a 60-mile-plus thick layer of lubricant, allowing the plates to slide.
According to a three-year study, Earth's smallest plate, the Juan de Fuca Plate, which is on the West Coast of America, moved about 1.3 inches between 2004 and 2007. This means on average the plate is moving less than half an inch per year. However, as plates move at different rates, and in different directions, and because they have irregular shapes, collisions often occur. The East Pacific Rise in the South Pacific is where the fastest continental plate movement occurs. This can be more than 6 inches per year, according to IRIS.
As amazing as it might seem, the collision of continental plates can cause the formation of huge mountains. The Himalayas in Asia were created this way, 40 million to 50 million years ago. It has 10 mountains more than 26,000 feet in height, according to Earth scientist Timothy Kusky, Ph.D, including Mount Everest, Earth's highest peak above sea level. Continental plate collisions can also create volcanoes, cause earthquakes and lead to the formation of new islands.