Soviet leader Mikhail Gorbachev made history this week with his sweeping but bloodless purge of the communist hierarchy.

Even so, the Soviet Union had better brace itself for more such shakeups.Gone are 110 officials, including a quarter of the most senior members of the Communist Party's top policy-making body, who were pressured into resigning to make way for 24 of Gorbachev's younger supporters.

Never before has there been such a massive change in the party's Central Committee between party congresses, which are held every five years.

This change both demonstrates and increases Gorbachev's power while signaling just how serious he is about his often-thwarted program of social and economic reforms.

Despite the huge scope of this purge, plenty of Gorbachev's opponents still retain power, including those holding posts in the Central Committee. Chief among them is Boris N. Yeltsin, the former Moscow first party secretary.

Though Gorbachev linked this week's resignations to last month's unprecedented elections in which several powerful party bosses failed to gain seats in a newly created national legislature, none of those bosses lost their seats on the Central Committee. That can't set well with the voters.

Moreover, the Sovietpeople seem bound to remain restive as long as the economy stays sour, and the prospects for improvement are not encouraging. The Los Angeles Times, for example, reports that market shelves in Moscow are now so bare that "they are reminiscent of the days immediately after World War II when an exhausted Soviet Union was still trying to pull itself together." Though savings soar, it's because there is so little to buy.

What's more, a recent report from U.S. intelligence agencies warns that Gorbachev's efforts to reform the Soviet economy along free market lines may be doomed because he has deliberately delayed imposing price reforms that would make consumer goods reflect the cost of production without government subsidies.

Other highlights of the report:

- The Soviet economy is meeting only 80 percent of the country's consumer demands, and food prices at collective farm markets have increased nearly 20 percent since Gorbachev assumed power in 1985.

- The Soviet deficit has ballooned in recent years, accounting for more than 9 percent of the gross national product in 1988 - about three times the U.S. deficit.

- The Soviet gross national product grew only 1.5 percent last year, well below the announced official figure of 5 percent, while the American economy in 1988 grew 3.9 percent.

- The gap between U.S. and Soviet technology is wide and growing, with the United States having a 15-year lead in some key computer technologies.

- Despite Gorbachev's pledges, there is still no evidence of a slowdown in Soviet military spending.

This situation adds up to a Soviet Union that certainly needs to shake up the ruling hierarchy and bring in more flexible leaders, as Gorbachev is doing. But it's also a Soviet Union with such serious problems and deep-seated dissatisfactions that Gorbachev's hold on power cannot always be taken for granted.