75,000 Evacuated as Mexican Volcano Rumbles : Latin America: Residents of 16 villages flee amid fears of an imminent eruption. New peril comes amid other national crises.

Fearing an imminent eruption of the Popocatepetl volcano outside this nation’s capital, the army and civil defense forces Thursday began emergency evacuation of 75,000 residents from 16 villages, as President Ernesto Zedillo’s government struggled with a series of economic, political--and now, natural--crises just three weeks into its term.

With hundreds of other troops and riot police moving deeper into the mountains in the southernmost state of Chiapas, where Indian rebels took over dozens of villages in a peaceful one-day insurrection on Monday, Zedillo was forced to call on the army again in Mexico City: Experts determined that a towering plume of black smoke from Popocatepetl on Wednesday could herald a major eruption of the 17,887-foot mountain.

Authorities were on alert, preparing to implement a sweeping emergency plan for the region after 5,000 tons of ash coated dozens of villages in the state of Puebla, east of the capital, throughout the night.

Mexico’s National Center for Disaster Prevention announced that a minor quake followed underground explosions Wednesday that were so intense they melted the snow on the peaks of the mountain known here as “Popo.”

The blast of smoke and ash followed weeks of intense seismic activity inside Popo, which last erupted in 1947. U.S. and Mexican scientists have expressed increasing concern that the volcano was becoming dangerously active, and environmental groups have sharply criticized the government for failing to prepare nearby residents for their evacuation.

The threat of an eruption that could endanger millions of Mexicans came against the backdrop of brewing economic and political disasters that are already testing Zedillo’s government.

Less than a month into a term that Zedillo vowed would usher in historic change, the 42-year-old economist and his young government are defending themselves not merely on natural-disaster preparedness but also on their handling of the Chiapas troubles and an ensuing financial crisis that Zedillo asserts is related.

Zedillo’s financial advisers performed radical surgery on the Mexican economy late Wednesday night, allowing the nation’s currency to float freely against the U.S. dollar.

And in a speech to economists, the president made an effort to justify the peso’s free-fall as economic medicine needed for long-term stability--although it will likely trigger higher inflation, cuts in spending power and continuing financial instability well into 1995.

In the same speech, Zedillo took pains to defend his Chiapas policy and explain how the two are linked.

“There cannot be economic stability if there is no political stability,” he said, conceding that his government must redouble efforts to negotiate a peaceful solution to the conflict in the embattled state, which began last Jan. 1.

But the president took no additional action on the uprising by the Zapatista National Liberation Army and its peasant supporters. He simply repeated his commitment to a proposed legislative peace commission to negotiate a political settlement.

Coming less than a week before Christmas, the series of crises intensified public criticism of Zedillo, who was shown to have 58% of popular support in public opinion polls just a week ago.

“Merry Christmas????” said the headline on an editorial in the independent daily Reforma on Thursday. The newspaper sharply questioned Zedillo’s political skills and his timing in permitting the radical peso devaluation within days of one of this overwhelmingly Catholic nation’s most important holidays.

Signaling that the president’s brief honeymoon with the Mexican press may be nearing its end, the same editorial page carried a cartoon illustrating what several analysts said was increasing dissatisfaction with the new administration.

In a clear poke at Zedillo’s Chiapas strategy, the cartoon shows a frantic bureaucrat in coat and tie, pointing at Popo and shouting to the president, “Sir, Popocatepetl is threatening to explode.”

A pensive Zedillo, drawn in enormous wire-rim glasses with hand on chin, responds, “We’ll form a commission and ask it what it wants.”