MEXICO CITY, July 10 (Xinhua) -- Researchers and authorities in Mexico are investigating a site in central Mexico's Michoacan state that is registering sudden signs of geothermal activity, the state government said on Monday.

Local residents in the northwestern town of Venustiano Carranza notified the authorities Sunday afternoon after noticing steam and incandescent material being emitted through cracks in the ground at a football field.

Researchers have measured temperatures as high as 250 degrees centigrade at the field in the community of Pueblo Viejo, located 227 kilometers from the state capital Morelia.

Video footage posted by local media showed steam rising from the ground, which easily gave way underfoot.

The state coordinator of Civil Protection, Pedro Carlos Mandujano, said researchers had yet to determine the cause of the high temperatures, but were inclined to rule out volcanic activity.

"We can't say this is the birth of a volcano, because up to now there has been no telluric activity at the site," said Mandujano.

In 1943, a volcano suddenly rose out of a cornfield in Michoacan. The Paricutin volcano, which buried two towns under lava before becoming dormant, is today a tourist attraction.