Despite continuing risks, many big-debt nations are pulling ahead

George M. Salem likens the developing-country debt situation to Mt. St. Helens. ''We don't know when the debt crisis will erupt again,'' says the bank stock analyst with Donaldson, Lufkin & Jenrette.

There has been much progress in dealing with the debt problem. Argentina has reached a tentative agreement with the International Monetary Fund on a domestic austerity program in return for a loan. Brazil and Mexico, the two largest debtors, have enjoyed huge increases in their trade surpluses. Mexico has negotiated a long-term rescheduling of its bank debts, eliminating annual hassles over debt payments.

Further, interest rates have nosed down from their summer peak. That saves the developing countries billions. Mr. Salem knows all this. Nonetheless, he says, ''the situation is far too unstable for it to remain dormant much into 1985.''

The Mexican debt crisis of 1982 shows that trouble in one Latin American nation quickly transfers to lender fears and financing problems for other countries. Salem says that ''there is validity to a domino effect. The Latin American LDCs (less-developed countries) are especially closely linked, and there is a rub-off effect from any adversity.''

He speculates on various events that might stir up the crisis again: Argentina could break off talks with the IMF and the commercial banks as a result of union pressure for high wages. Mexico, Venezuela, and Nigeria could suffer a sharp loss in creditworthiness, should oil prices and production plunge. Brazil's new president, to be elected Jan. 15, could announce he will be tough on the banks and the IMF.

Philippine President Ferdinand Marcos or Chilean dictator Augusto Pinochet might be overthrown, prompting chaos in their countries. A large debtor nation could ask for a multibillion-dollar jumbo loan of fresh money and is refused by the banks. Regulators could mandate reserves or write-offs on loans to a major debtor or two - say Argentina. Banks then would be less willing to lend.

Of course, none of these may happen. And if one of these events does occur, it need not start a chain reaction. But what if a ''worst-case scenario'' occurs - if several of the major debtor countries default at once?

''Nobody knows,'' says William B. Dale, former deputy managing director of the IMF. ''You have to play it by ear.''

Nonetheless, Mr. Dale, who served 10 years until last June at the IMF, says he remains an optimist. He recalls developments after Mexico told the fund on July 23, 1982, that it would not be able to continue meeting payments on its external debt. ''It appeared we might be on the edge of that worst-case scenario ,'' he said. ''So we scrambled around.''

The rescue operation ''may not have been clean and intellectually satisfying, '' he said. But it was a success. Similarly today, if a worst-case event actually occurs, ''something'' can be done, he figures.

Another reason for his optimism is the progress already made by the debtor countries. In a recent lecture at the Fletcher School of Law and Diplomacy at Tufts University, Dale noted that ''balance-of-payments adjustment in most of the heavily indebted countries has proceeded faster and further than could reasonably have been envisaged - or was envisaged - earlier.''

To many, he says, a global problem of debt should have a global and systematic solution. For instance, the Cartagena group of 11 Latin American nations has met several times and issued a call for a meeting with creditor countries to deal with the international debt crisis. In late September agreement was reached for the IMF Interim Committee and the joint World Bank/Fund Development Committee to hold extended meetings next April. Management of the debt problem will be discussed in a medium- to long-term framework.

Mr. Dale does not expect these discussions ''to alter significantly the characteristics of the handling of the debt problem, either substantively or procedurally.'' In fact, he prefers the present country-by-country approach: ''With adjustment ahead of schedule and growth beginning to come through (in the developing countries), shifting course would be a hazardous exercise indeed for these countries.''

So, for the time being, the world's financial officials will sit on the flanks of their debtor volcano, dealing with any eruptions on a case-by-case basis. And Mr. Salem will continue to recommend against holding money-center bank stocks for the long term.