CHICAGO, Jan. 20 (U.P.)--Japan is sitting on a huge powder keg whose tremendous forces could wreak more destruction throughout the island empire than all the bombing planes in the world, according to Dr. Helmut Landsberg, University of Chicago seismologist.

Landsberg said the Japanese islands are the most active earthquake region in the world. As many as 400 temblors are recorded each year, usually of such minor nature as to be detected only by delicate seismographs.

"But every 20 or 30 years a quake of tremendous dimensions hits the islands," he said. "That's when the big blowoff comes. The last terrible shock hit Tokyo in 1923, so that from statistics we can be reasonably sure that Japan will suffer another one sometime after 1943."

(Harvard's internationally known earthquake authority, Lewis Don Leet, assistant professor of Seismology, was out of town yesterday and could not be reached for comment on Landsberg's statement, but one of his assistants indicated that Professor Leet did not think that the U. S. could count on a Japanese earthquake to win the war.)

The 1923 quake killed 100,000 Japanese and did unaccountable property damage. Much of the nation's industry was disrupted while people rebuilt their cities.

Neglected Anti-Quake Construction

"If such a quake hits them again, it will certainly upset the Mikado's apple cart," Landsberg said. "Most of the dwellings in Tokyo and Yokohoma are flimsy, wooden things. It would take months of concentrated bombing to equal that damage inflicted by a sudden release of the tremendous energy stored in the bowels of the earth."

He said that in California, another active quake region, buildings are anchored to solid rock which shifts less than sand or gravel foundation bases.

Japan had neglected anti-quake building construction for war implement production. Landsberg said, "when the sleeping monster" beneath the islands once more awakens Japan stands to suffer a loss equal to, if not greater than, that resulting from the 1923 temblor.

May Doom Jap Aggression

"There are some interesting sidelights to this matter of earthquakes," Landsberg said. "With minor shocks coming so often, it must be difficult for the Japs to protect their harbors and naval bases. I don't know how much it takes to set off a sea mine, but I have a hunch that the little men are having trouble keeping their mines anchored to the ocean floor."

Landsberg said it is "quite conceivable that the ringing of alarm bells and quivering of seismograph needles in American universities may mark the end of Japan's aggression attempts and the proper time for the Allies to strike back at the islands.