SO MANY TIMES in so few months, violence-- gunshots, burnings, stone-throwing and looting --has erupted in Miami. What is happening to set off three such social explosions in 31 months? The temptation is to respond with the generalizations of more than 14 years ago, when similar upheavals rocked other cities. But there are also local circumstances that can be critical as factors in this kind of violence. And Miami has its volatile share:

Long before the hell that broke loose in May 1980, many residents sensed violence in the wind. Relations between police--that could read mostly white police-- and black residents were not good at all. Various incidents had stirred feelings that mistreatment by white authorities was going unpunished while blacks were suffering the worst punishments. Unemployment among blacks was double what it was among whites, while a surge of Cuban and Haitian immigrants was threatening to take many of the few jobs around and to divert government money and attention--neither of which was all that abundant. After considerable study in the aftermath, then-attorney general Benjamin Civiletti cited "a great perception of injustice, which has brought a sense of frustration and rage."

Sound depressingly familiar? Millions of federal dollars have been spent, many studies have been commissioned and completed, members of the Miami and Dade County police forces have been given special training. But officials are still hard-pressed to cite any new jobs created in the black neighborhoods, and news of a black death after gunfire from a police officer--no matter the details--can set off a melee.

Without reading too much into similarities, there is danger that the aftermath will be no different, either: after the shock, some introspection and a little rebuilding, maybe. Then business as usual?

Two years ago, members of the U.S. Justice Department's small and underused Community Relations Service said they had been aware of Miami's troubles "for the last 10 years" and they had been warning about police-community relations all along. "They're listening now," said one. "It's usually before a riot that they don't listen."

How long and carefully will they listen now? At this point, talk about federal dollars and jobs--even if there were a lot of both to offer--falls on deaf ears in the streets. The answers don't come easily, and neither does the kind of sustained effort necessary to find them. In the meantime, that perception of injustice lingers menacingly.