Authorities warn people to stay away from the volcano near Mexico City after 200 minor eruptions are recorded in 24 hours.
It has issued a level three yellow alert, indicating possible magma expulsion and explosions of increasing intensity.
The alert – the third highest – is one level below a red alert that would trigger preparations for an evacuation.
The 17,900ft (5,450m) stratovolcano has been particularly active in recent months and has now been spewing hot rock, ash and gas.
It has sent pieces of burning rock showering about one and a half miles (2.4km) down its slopes, which has caused fires in surrounding grassland.
Several towns reported ash falling on them from the explosion.
Some 25 million people live within about 60 miles (97km) of the volcano’s crater.
A major eruption at Popocatepetl in 2000 forced an evacuation and saw nearly 50,000 residents in three states surrounding the peak flee the region.
The Mazatlan Post