Moderate ash plume at Mexico's Popocatépetl

A lot of volcanoes produce 3-km ash plumes on the regular basis. Right now, there are probably two or three volcanoes in Kamchatka or Indonesia alone that are generating plumes of that size or larger - but those volcanoes are not looming over a population center like Mexico City. That is why every little noise Popocatépetl makes it watched carefully - and makes the news, especially in Latin America, as the Mexico City area has over 20 million people in its metropolitan region. Popo (for short) is about ~55 km from Mexico City and 45 km from Puebla (see map below). It has a history of frequent vulcanian eruptions in the VEI 1-3 range, and one in ~3,700 B.C. that was a VEI 5 eruption that produced pyroclastic flows, lahars and the growth of a new dome. Pyroclastic flows, ash and lahars are the primary hazards from Popocatépetl and it is one of many volcanoes that span the middle of Mexico, including Colima and Paricutin.