November 16, 1985

Prime Minister Margaret Thatcher signed a treaty here today giving the Irish Republic a formal consultative role and official presence in this province, long a sectarian battleground. It was the first such arrangement since Ireland's partition 65 years ago. Under the potentially far-reaching accord, the Dublin Government is given a mechanism for pressing its views on virtually all matters touching the Roman Catholicminority here, including the security policies of the army and the police, the administration of justice and prisons. This is to be done through a joint secretariat of Irish and British officials to be set up here, officials said, within a matter of weeks to serve a ''conference'' of Cabinet ministers from the two countries that will be more or less permanently in session to discuss sensitive issues and matters of policy.

Benjamin Rojas stood on the roof of San Lorenzo Hospital and stared out over a vast expanse of gray mud. ''Thousands of people are buried under there,'' he said. Pointing to a house-sized boulder, he added, ''My family is under there.'' Mr. Rojas was one of a handful who scrambled to high ground after the Nevada del Ruiz volcano erupted Wednesday night, setting off an avalanche of mud and rocks that roared through this sleeping town of 25,000.

IJust before the Geneva summit meeting, Defense Secretary Caspar W. Weinberger has sent President Reagan a letter urging him not to make any agreements involving two key aspects of arms control. Mr. Weinberger, who will not be attending the Geneva conference, asked the President to avoid a commitment not to undercut the unratified 1979 strategic arms treaty or one that would affirm a ''restrictive'' interpretation of the 1972 antiballistic-missile treaty. Such an interpretation, he said, would hurt Mr. Reagan's program to develop a defensive system against ballistic missiles. The program, the Strategic Defense Initiative, is popularly known as ''Star Wars.''

The Soviet Union, apparently in a gesture in advance of the summit meeting next week, today told the United States that it would give exit visas to some American citizens' spouses who for years have been denied permission to leave, State Department officials said today. One official said the Foreign Ministry had provided a list of 10 names to the United States Embassy in Moscow. Eight of them are separated from their spouses, one was described only as a member of a divided family and another was described as a ''longstanding dual-national case.'' A State Department spokesman said, ''If these cases are indeed resolved as a result of these assurances, we would view this as a welcome step.''

Rescue workers struggled today with the immense task of saving survivors and recovering thousands of bodies from the sea of mud that destroyed this town and severely damaged 13 communities after the eruption Wednesday of a long-dormant volcano. The Government said tonight that 21,559 people were dead or missing in Armero and the other communities around the Nevada del Ruiz volcano. Officials said they had counted 1,433 injured so far, but this figure was expected to rise. 'Don't Have the Help We Need' Raul Alferez, a 20-year-old volunteer Red Cross worker who was leading the rescue operation here, said that while there were reports that tons of emergency equipment and supplies were pouring into Colombia, the material had not yet reached Armero, a town of 25,000, which was hardest hit. ''We don't have the help we need,'' he said, standing to one side of a roped-off square of grass that serves as the main aid station here. ''We need people and we need equipment. We need more helicopters and we need stretchers, gauze, anesthetics, all kinds of first-aid equipment.''