"The Defense Department has taken an overly pessimistic, scientifically in-valid position on detection of under-ground nuclear tests, ignoring the opinion of professional seismologists," Lewis D. Leet, professor of Geology, charged yesterday.

The U.S. view that seismographic detection is unreliable will be of great importance if the Geneva disarmament conference renews test ban talks, Leet said. U.S. officials, contending that detection is too difficult to be an effective control, demand that a treaty prohibiting tests include extensive inspection checks.

Delegates of the Soviet Union with-drew from 1959 test ban discussions then the U.S. made new claims for inspection based on what Leet termed supposed seismological data." The Soviets at that time bitterly criticized the technical data used by the U.S., and held that accurate detection is possible.

Leet challenged the March 4 report of Project Vela, a recent Defense Department research program of detection experiments in Nevada. The report was appproved by the Atomic Energy Commission and the State Department.

"Project Vela's conclusions, which confirm the Defense Department's 1959 and, exaggerate the problems involved," the seismologist argued.

A major difficulty confronting Project Vela was distinguishing the seismic waves caused by underground nuclear explosions from those of earthquakes. Leet was confident that a solution to this problem could be found "with proper instrumentation and research. No adequate scientific inquiry into the entire area of underground nuclear test detection has yet been made."

Political Implications

He said it is possible that the government investigation, which "seems to be run by anonymous panels and ad hoc committees," is using its technical material to support a political position. "Perhaps they only want an excuse to call for inspection in Russia," he ventured, "but they cannot correctly use seismology as justification."

"U.S. diplomats in Geneva are not equipped with full knowledge," Leet declared. "I am trying desperately to let people in authority know that the seismological information given them is scientifically unsound."