Mexican authorities raised the alert level for “Popo,” as it is nicknamed, after the mountain started spewing red-hot rock fragments into the sky and propelled a vapor cloud a mile into the air.
Located some 50 miles southeast of Mexico City, the lava dome on the 17,900 foot (5,450 m) volcano began expanding on Friday, said Mexico’s National Center for Disaster Prevention.
Worried that this could provoke big explosions capable of sending incandescent fragments out over considerable distances, as well as ash showers, the center raised the alert level to yellow phase three, the third-highest warning on the center’s seven-step scale.
Popo’s latest fuming comes amid a series of earthquakes striking southern and central Mexico in the past three weeks.
Events like Sunday’s serve to prevent more dangerous pressure from building inside the volcano, scientists say.
Thanks to Robert Stom and Laurel for these links