Theoretical Introduction
First, let's clarify what is meant by collapse - the collapse of the Classic civilization that occurred sometime near the end of the 9th century, was apparently a devastating event, but seems to have been contained to the Peten/highland areas. In the Northern Lowlands, sites like Coba and old Chichen Itza seemed to have continued without much of a problem for many more generations, and sites in the Puuc Hills were just beginning to flower. So it is assumed that the question pertains to the "demise" of the Central area sites. Most "Mayanists" seem to agree that the collapse was due to a combination of problems, but none seem to agree on what was the dominant cause. Perhaps there was no dominant cause. For example, if you were to look at the USSR - what would you say was the dominant cause for its collapse? It is doubtful that anyone could get all contemporaries to agree - so how could we expect to reach a consensus on something that occurred long ago with no written records.
The Maya Collapse refers to the decline of the Mayan Classic Period and abandonment of the Classic Period Maya cities between the 8th and 9th centuries. The classic Maya collapse is one of the biggest mysteries in archeology. To this day, nobody knows where the Maya people came from before they arrived in the Yucatan Peninsula, and nobody knows why they left or where they went when most Mayans abandoned their cities and disappeared from the peninsula.