Scientists recorded two moderate explosions Saturday morning at Mexico's Popocatepetl that sent columns of gas and ash up to 2.5 kilometers (1.5 miles) above the crater, the National Disaster Prevention Center, or Cenapred, said.

The latest bulletin on this volcano in central Mexico said the first explosion occurred at 6:46 a.m. and the second at 10:00 a.m.

Cenapred said the system also recorded different tremor episodes Friday afternoon and shortly after midnight, adding that those seismic signals were accompanied by the regular emission of a plume of water vapor, gases and small quantities of ash.

Mexican authorities are maintaining a phase 3 yellow alert, the level below the one that would require evacuations of nearby populations.

They have closed roads within a 12-kilometer (7.5-mile) radius around the volcano, while vehicular traffic is restricted between the towns of Santiago Xalitzintla and San Pedro Nexapa.

Some 700 military personnel are on alert in case an increase in volcanic activity triggers a phase 1 red alert that would require an evacuation of the zone closest to the volcano.

The summit of Popocatepetl, Mexico's second-highest mountain and one of the country's 14 active volcanoes, is 5,452 meters (17,875 feet) above sea level. EFE