Alert level raised for Popocatépetl volcano in Mexico

Mexico on Sunday raised the alert level for the Popocatépetl volcano to "yellow phase 3", which is just below the "red" alarm level. 

Hundreds of tremors have been registered in the region in the last week, officials said. The volcano has been spewing smoke and ash. 

The parameters for "yellow phase 3" are low to intermediate explosive eruptive activity, mild to moderate explosions that can hurl rock fragments, and light to moderate ash falling in surrounding towns and more distant cities, the National Center for Disaster Prevention said. The expulsion of magma is also possible.