Keywords: Los Humeros.jpg The broad ridge in the distance to the NW is Los Humeros the easternmost of a series of large silicic volcanic centers with active geothermal systems located north of the axis of the Mexican Volcanic Belt http //www volcano si edu/world/volcano cfm vnum 1401-093 volpage photos photo 085083 2000 Lee Siebert Smithsonian Institution PD Smithsonian Institution is administered by the U S government Photos taken by Smithsonian Institution's employees are thus without restriction confirmed by Mr Edward Venzke from Smithsonian Institution PD-USGov Volcanoes of Mexico Calderas Volcanic centers |