More than 25 million years ago, India, once a separate island on a quickly sliding piece of the Earth’s crust, crashed into Asia. The two land masses are still colliding, pushed together at a speed of 1.5 to 2 inches a year. The forces have pushed up the highest mountains in the world, in the Himalayas, and have set off devastating earthquakes.

Experts had warned of the danger to the people of Katmandu for decades. The death toll in Nepal on Saturday was practically inevitable given the tectonics, the local geology that made the shaking worse and the lax construction of buildings that could not withstand the shaking.

GeoHazards International, a nonprofit organization in Menlo Park, Calif., that tries to help poorer, more vulnerable regions like Nepal prepare for disasters, had noted that major earthquakes struck that region about every 75 years.