Security Pacific Corp.'s disclosure this week that it will lose as much as $360 million in the fourth quarter is the latest in a string of bank problems nationwide that has put to a test the public's confidence in the nation's banking system.

Virtually every day, more bad news surfaces from the corporate suites or the halls of Congress. On Tuesday, for example, Federal Deposit Insurance Corp. Chairman L. William Seidman issued a pessimistic warning that recent declines in bank profits and soft Northeast real estate prices will result in a $4-billion loss for the nation's bank insurance fund this year. That is about $1 billion more than previously projected and leaves only $9 billion to insure $2 trillion in deposits.

Comptroller of the Currency Robert L. Clarke, the chief regulator of national banks, said in a recent speech that the industry's image is more tarnished now than it has been since the Great Depression. "Bankers don't have a reservoir of public goodwill from which to draw," Clarke said.

But, despite the flurry of bad news, the banking industry's slump is selectively choosing its victims. Some of the nation's largest banks--Chase Manhattan, Bank of New England and Security Pacific--have disclosed huge problems. But, some large banks have remained highly profitable, such as J. P. Morgan in New York, BankAmerica Corp. and Wells Fargo & Co. in California, First Wachovia in North Carolina and Banc One in Ohio.

Few expect banks to go the way of savings and loans. Unlike banks, thrifts skated on a thin layer of funds invested by their owners. In some cases, disreputable managers easily took control of thrifts. Supervision was lax, and accounting gimmicks made some savings and loans appear healthier than they really were.

But many banks did expand into risky areas in the 1980s and will be paying for it in the 1990s. Commercial real estate markets are in a free fall in some areas. High flyers such as developer Donald J. Trump are having trouble paying their debts. Credit card delinquencies are rising. And companies that borrowed heavily to finance buyouts are squeezed.

As deep as banking's problems are, depositors have little to worry about. Generous federal deposit insurance backs accounts up to $100,000. Indeed, as big as the savings and loan scandal is, hardly anyone has ever lost money deposited in a thrift. That's because taxpayers shoulder the losses, estimated at $600 billion over the next 40 years.