Finally, eyewitness descriptions match the traditional description of the Chupacabra, said to resemble a kangaroo and a dog with huge teeth.

"I heard the sheep bleating loudly, and when I approached the barn I saw a black shadow, like a big dog standing on its hind legs. It leaped like a kangaroo - when it spotted me it ran away," says Yerbulat Isbasov, 18, who guards sheep in the village of Gavrilovka.
Yerbulat saw the beast again in a few days' time, and described it as a 1.2 meter high animal with a hump on its back.

Alfia Makasheva saw a whole pack of vampires in her yard.

"One was a huge reddish thing, another was dark grey, and they were being followed by a pack of pups. In the middle of the yard the red one turned its head and got up on the hind legs, as if it was thinking."

When Dmitry Madinovsky from Orenburg heard about the beast, he suggested it could be the legendary Chupakabra, and set off to look for it. In the woods near the Sakmara river he discovered two rows of tracks that could belong to an animal of some 35 kilos in weight. The tracks were of five-toed paws with claws and webbed fingers, and a tail that dragged between them. Zoologists could not identify the animal from photos of the prints.

"It is definitely a Chupakabra! Small front and big hind legs," Madinovsky says. "The animal first walked on all fours, near the water it got up on its hind legs, raised its tail and leapt away like a kangaroo."

This May Madinovsky and the Urals Anomaly Monitoring Station experts are determined to track the animal down.

The area, also known in military circles as Whiskey 291, covers 1 million square miles and is off-limits to civilian planes and ships, Fiebing said.

"There was no unusual training that would have caused anything close to what people here felt," he said.

Cmdr. William Fenick, another local Navy spokesman, said no San Diego-based warships were conducting operations in Warning Area 291 that day.

"We don't know at this time where this earthquakelike sensation came from," Fenick said.

The April 4 disturbance hit San Diego County shortly before 9 a.m. A quake was quickly eliminated as the cause, leaving a mystery that has been the source of three weeks of speculation from Pacific Beach to Lakeside to the Internet.

The Scripps researchers believe the disturbance was the result of a low-frequency wave that traveled through the air at the speed of sound as it moved from the ocean to the desert. It was picked up by more than two dozen seismometers in San Diego and eastern Riverside counties, the researchers said.

According to data analyzed by the scientists, the wave was felt on San Nicolas Island, northwest of San Clemente Island, at 8:40 a.m. It hit Solana Beach at 8:46 a.m., the western edge of the Cleveland National Forest at 8:47.30 and the eastern side of the Salton Sea at 8:53 a.m. From there, it appears to have dissipated.

Elizabeth Cochran, the lead researcher on the project, said the wave moved at 320 meters per second, roughly the speed that sound travels through the air. Its velocity was too slow to be that of an earthquake, she said.

Cochran, a postdoctoral researcher in the geophysics and planetary physics department, said the only explanation is that the wave was traveling through the atmosphere, not through the ground. At each location, the wave could be felt for roughly 10 seconds, she said.

Several months before the April 4 incident, the team had begun studying other nonquake disturbances that were registering on San Diego County seismometers, including 76 that apparently originated in that same general area of the ocean in 2003. Shearer said he and his colleagues figured that some of those disturbances surely must have come from offshore military exercises.

The researchers haven't been able to determine whether the April 4 wave was more powerful than the earlier ones or whether it simply felt that way because of atmospheric conditions.

If the disturbance was caused by the military, no one has owned up to it. The Navy and Marines say none of their planes were flying at supersonic speeds that morning.

"I'm told that a sonic boom would not cover that distance at all," said Fiebing, the Navy spokesman.

The Navy uses Warning Area 291 for a wide range of training, including large-scale ship maneuvers and battle exercises, but Fiebing and Fenick said they were unaware of any such training April 4 that would have caused such a disturbance.

Authorities have said a meteor probably wasn't the cause because it would have been noticed by the scientific community. The American Meteor Society reported no fireball sightings over Southern California on that day.