The Mayans Lived on Volcanically Active Ground
It’s never safe to build your civilization next to a volcano. The Mayans had to learn that lesson the hard way during the El Chichón eruption in 540 AD. The sky turned black with smoke, blocking the sunlight. That would not have been good for crops, but that would have been the least of their problems. The smoke from the volcano would have been filled with microscopic pieces of glass. Inhaling it would have resulted in irritation and microscopic cuts in their lungs. Even if you survived the initial eruption, the sulfur thrown into air would have blocked out so much sunlight as to decrease global temperatures by 2 degrees Celsius! Crop yields would have been devastated. The poor harvests resulted in both the Maya and Inca revolting against their rulers. This was the beginning of the Maya Dark Age. For 100 years, no buildings were constructed.