Alexander von Humboldt climbed El Jorullo during the Mexican portion of his scientific expedition to Spanish America.

When he visited on 19 September 1803, its multiple cones were still smoldering and the air was extremely hot and filled with volcanic gases.

Humboldt also notes that he consulted a 1782 publication Rusticatio Mexicana, by Rafael Landívar, who calculated the height of the volcano and the temperature of the thermal waters.

[5] El Jorullo did not develop on a corn field like Parícutin did, but it did destroy what had been a rich agricultural area.

Called the Trans-Mexican Volcanic Belt, the region stretches about 700 miles (1,100 km) from east to west across southern Mexico.

The eruptive activity deposited a layer of volcanic rock some 6,000 feet thick, creating a high and fertile plateau.

During summer months, the heights snag moisture-laden breezes from the Pacific Ocean; rich farmland, in turn, has made this belt the most populous region in Mexico.