PASADENA, CALIF., AUG. 27 -- Neptune's bizarre moon Triton may have active "ice volcanoes" in its southern regions that are shooting nitrogen ice plumes 20 miles into the atmosphere, according to the latest close-up images from the robot Voyager 2 space explorer. "I believe these things are occurring now," said Laurence Soderblom of the U.S. Geological Survey, a leader on the Voyager team that analyzes the pictures returning from deep space. His theory, which he described as a "crazy idea" that erupted just this morning when he saw the pictures, strengthens the view of Triton as an unusual moon with a violent past that has spent billions of years "busting out all over": oozing, squirting and generally welling up. But until today, scientists thought it had gone into a frosty retirement. Soderblom suggested that pools of supercold liquid nitrogen below Triton's surface continuously wend their way up toward openings at the surface, where atmospheric pressure is so low that the liquid explodes into gas and ice. The dark "tails" seen in the images as streaking northeasterly, in lengths up to 45 miles, result when emerging nitrogen scrapes darkened material from "the sides of the gun barrel," as one scientist put it, and this is deposited on the white surface ice. The nitrogen shoots out at speeds up to about 112 mph, with an assist from the prevailing nitrogen winds on Triton, Soderblom said. Soderblom said he believes the volcano-like features are active now because they appear to be deposited on a retreating ice sheet that disappears seasonally. There are "lots" of these visible in images of the southern hemisphere. There is nothing exactly like them on Earth, but they share elements of volcanoes, Yellowstone Park-type geysers and Artesian wells, scientists said. Soderblom's announcement brought gasps of astonishment from scientists and reporters gathered at the Jet Propulsion Laboratory, which is managing the Voyager mission for NASA. It was the latest of a series of stunning findings pouring from the Neptune encounter that climaxed early Friday. Scientists also reported yesterday that:Neptune, looking more like the cockeyed planet Uranus, has a magnetic field whose poles are tilted at least 50 degrees relative to the axis around which it rotates. Measurements the day before had put it at a 30-degree tilt. The planet's giant storm, the Great Dark Spot, has winds up to 760 mph relative to the planet's interior. Scientists played a tape of Voyager 2 passing through a bombardment of dust particles at a rate of 300 per second in the plane of newly discovered rings around Neptune. It sounded like heavy rain on a tile roof. Soderblom cautioned that his volcano theory is "a crazy idea. It's probably wrong, but it's the best we have at the current time." His uncertainty, he added later, is mostly in the details rather than the general theory that nitrogen is somehow "squirting" into the atmosphere. Soderblom's caveat is counterbalanced by his reputation as a leading scientist who is more willing than some of his colleagues to express "brilliant ideas" at an early stage and let others watch the process of proof, according to some who know him. "He is usually right," said one colleague. "This is Larry's style. He likes to think out loud," said planetary scientist Bradford Smith, leader of the Voyager imaging team. "I think {the theory} is a very good idea." If the theory is right, it makes Triton the second body, other than Earth, found to have active volcanoes, Soderblom said. Jupiter's satellite Io is the other. The two Voyager spacecraft observed nine eruptions in progress when they arrived in 1979. Scientists believe there may also be active eruptions on Venus. Scientists have only begun to consider possible mechanisms by which the eruptions might occur, Soderblom said. "We just happened on this idea about 9 o'clock." Some scientists had theorized earlier that the blackened plumes were the result of "scouring" -- surface movement of darkened material -- by Triton's prevailing nitrogen winds. But Soderblom and others contend that Voyager's instruments have shown Triton's atmosphere to be too thin for such an effect.