YINCHUAN, China - Tech-savvy armchair sleuths around the world are having a field day discovering military secrets in China.
Three times in the past few months, they've stumbled across unusual military installations using Internet programs that allow those online to view satellite and aerial images of the world.
In the most recent find, users spotted an underwater submarine tunnel off China's Hainan Island. They've also found a mock-up of a Taiwanese air base in China's remote western desert. In a bizarre discovery, a computer technician in Germany noticed a huge and startlingly accurate terrain model in northwest China that replicates a sensitive border area with India.
The discoveries have stirred up the Internet global-imagery community.
"You can sort of feel the feverish buzz of these guys," said Tim Brown, a satellite imagery expert at GlobalSecurity.org, an Alexandria, Va., research center on security issues.
Defense experts such as Brown are quick to point out that civilians are unlikely to find anything that skilled military analysts haven't already known about and studied in detail.
But the discoveries underscore the shifts occurring as satellite images no longer remain only in the hands of a fraternity of military and intelligence agents but fall into a broader civilian realm. Some countries such as India, Bahrain, Russia and South Korea are spooked at the idea that ordinary people - or worse yet, terrorists - might see satellite images of installations such as military bases, presidential palaces and nuclear reactors.
There's little they can do to stop such services as Google Earth or MSN Virtual Earth, though. And geographers, hobbyists and those with time on their hands have taken to combing the satellite images for hitherto unpublicized military sites.
"There are people out there who basically scour the Earth looking for this kind of thing," said Stefan Geens, a Swede who runs a Web journal, Ogle Earth, about imagery. "It's a new kind of pastime or hobby. It's democratization of this kind of information."
In early August, bulletin boards operated by Google Earth aficionados surged with the news that users had spotted an unusual coastal cave entrance southwest of the Yulin naval base near the city of Sanya on Hainan Island, China's southernmost point. Since then, experts have determined that it's at least the second such Chinese oceanic tunnel to protect submarines in case of attack.
Another discovery was more serendipitous - and enigmatic.
One evening in late June, a Californian living in Germany discovered a topographical terrain model in northwest China. The replica, set in arid desert in the Ningxia Autonomous Region, includes artificial snow peaks, glacial lakes and valleys. Its fenced area is huge, measuring nine football fields long and seven wide.
Posting under the user name KenGrok, the American alerted a Google Earth bulletin board to the find. At the urging of a moderator, KenGrok scoured China's border regions to see if the terrain model replicated any existing territory.
Sure enough, it did. About two weeks later, KenGrok matched the model to a portion of the Sino-Indian border, Aksai Chin, at the east end of the Karakorum Range some 1,500 miles to the southwest.
So why has China built a "sandbox" model of its sensitive border with India?
A lot of Google Earth users became curious, and KenGrok parlayed his discovery into a blog titled "Found in China" that reaped global attention.
KenGrok declined to give his real name and voiced wonder at the interest that his sighting has generated.
"It's not like anyone is discovering the Sandwich Islands 300 years ago or anything like that," he said.
Specialized Web sites that reported the discovery were swamped with readers' views about the purpose of the site. It's to test satellites, opined one. No, it's a visualization training ground for pilots, said another. One wag said it was a huge miniature golf course. Still others suggested it was to study water drainage.
A McClatchy reporter traveled to the site and found an armored tank base surrounding it, near the village of Luoxi in Yongning County. Visitors weren't allowed in. Asked the purpose of the terrain replica, an army guard said: "It's for all kinds of military training. You wouldn't understand it."
A cement salesman in the nearby town of Huangyangtan, Ying Yujing, said he'd heard about the construction of the replica several years ago and went to see it himself.
"They built a replica of hills," Ying said. "They are very, very big. I went there because some people told me they could use cement." Ying wasn't able to make a sale.
Although India is one of the countries with national security concerns about satellite imagery, it may benefit from the China discovery. Some defense analysts think that the publicity brought about by more widely available satellite imagery defuses frictions while making military affairs more open.
India and China have good relations now, but fought a border skirmish in 1962.
"I really don't see a downside," said Theresa Hitchens, the director of the Center for Defense Information, a Washington research center on security and defense policy. "The more people have access to this kind of information, the more understanding you have."
Some 13 nations control imagery satellites, Hitchens said, though few operate ones with the quality of U.S. satellites. "They can see license plates on cars," she said.
Satellite images posted to Google Earth routinely are several months to two years old and of low resolution, making them of little use for aggressive purposes.
"It appears to be the consensus of security and military experts that images of the type available on Google Earth are unlikely to be of any value to terrorists," Debbie Frost, a spokeswoman for the Mountain View, Calif., company, said in an e-mail.
Weighing against security concerns, she said, were the benefits that the images provide in emergency responses to natural disasters.
China's neighbors have taken an interest in imagery. Earlier this year, Google Earth users spotted a faux base in Dingxin, Gansu province, that's a mock-up of Taiwan's Ching Chuan Kang base. China claims the island of Taiwan as part of its territory and says it has the right to use force for reunification.
Brown, of GlobalSecurity, said the discovery of the Hainan Island submarine tunnel had piqued interest among Philippine, Malaysian and Vietnamese military officers with an avid concern about China's ability to project naval power.
A lot of the Internet comments from Google Earth aficionados posting about things they spot are filled "with amateurishness bordering on ignorance," Brown said.
"People see a light (on an image) and say it's a UFO," Brown said.
Nonetheless, he said, combing through satellite imagery is something that anyone can do now: "It's a spectator sport, but it's no longer played just by professionals."
© 2006, McClatchy-Tribune Information Services.