MEXICO CITY - Authorities gave tens of thousands of people permission to return to their homes near Mexico's Popocatepetl volcano on Tuesday but warned them to remain on alert.
The announcement spelled the end of an evacuation that began Dec. 15, when scientists detected alarming tremors beneath the 17,886-foot mountain about 40 miles southeast of Mexico City.
On Dec. 18, Popocatepetl produced its most violent eruption in 1,200 years, though it caused no injuries.
After a relatively quiet week, the volcano spewed ash and hurled fragments of red-hot rock as far as a half-mile from the crater early Tuesday. Scientists said such eruptions could continue over the coming weeks as the volcano destroys a dome of lava in its crater, according to the Interior Secretariat.
But officials said in a government bulletin that there has been a ''notable reduction in the probability'' of a larger eruption, so they lifted the evacuation order on some 40,000 people living in about two dozen towns and villages.
Residents are still barred from coming within six miles of the crater, and residents of two towns closest to the volcano must have their houses inspected for damage from accumulated ash on rooftops.
The bulletin said scientists believe the volcano is still capable of hurling hot rocks some three miles and cooler rocks about six miles. The volcano could cause showers of ash hundreds of miles away, it said.
It was the second time in six years that the volcano had forced some residents to spend Christmas away from their homes.
The last evacuation occurred in December 1994, shortly after the volcano awoke after nearly 70 years of inactivity.