Natural gas blowhole
Now 53, Shen is the senior interpreter at Kenting National Park, where he also serves as a sort of local historian and naturalist. "When Hengchuen was built up by the Ching dynasty in 1876," he said, "there was more ground fire than now. There were at least five spots, but they have changed several times."
Pointing to a map, he showed some of the various points at which flames have shot from the ground between Hengchuen and Manchou along the Dongmen Stream. The shifts were likely due to seismic activity, he said, as the bed of the Dongmen Stream coincides with a local fault line.
The ground in the area is composed of mudstone, which is generally full of cracks and fissures. The fractures in the rock provide routes for the natural gas to seep up through the stone.
The gas ignites at the surface because it is heated to high temperatures while still deep in the ground. When it is finally emitted, it is hot enough to ignite spontaneously. "At Yellowstone [National Park in the US], they have similar underground heat," said Shen. "There it heats water and produces geysers. Here it heats natural gas."
In the rainy season, which covers the summer and fall months, the flames occasionally go out. Though heavy downpours cannot extinguish the flames, they can block the passages through which the gas escapes.
Historically, Shen said that many residents in the Hengchuen area were wary of the mysterious fires and held various superstitions about the Chuhuo region. "The flames coming out of the ground was very strange, especially when they moved, and they attributed it to spirits. However, a danger that was even more real in the 19th century for the Chinese settlers was the Paiwan Aboriginal tribe, who lived in the mountainous interior up along the Dongmen Stream. Sometimes people were attacked and killed there. There were also battles between the Chinese and the Aborigines. Because a lot of people died there, people were afraid the area was full of ghosts."
Now, however, the local population seems to be more or less scientifically enlightened, treating such ghosts stories as only so much nonsense. Mr. Zheng , a leathery old man who sits in the parking lot and sells ice cream by day and barbecue supplies by night, burst out laughing at first mention of my ghost hypothesis. "Good lord! Where did you get that idea?" he asked. "Read the sign! The fire here comes from natural gas!"
The last time Chuhuo shifted -- bringing it to its present location -- was in the 1960s after the China Petroleum Corporation (CPC) spent three years testing and drilling for natural gas in the area. Lu Ming-de (呂明德) of the CPC's exploration unit wasn't around for that prospecting mission between 1964 and 1967, but he was willing to say a few things about it. "Anywhere we detect seepage in Taiwan, we'll explore," he said. "But there needs to be tens of millions of cubic meters for it to be economical."
At present, the major natural gas deposits exploited by China Petroleum are in Hsinchu (新竹) and Miaoli (苗栗). "At Chuhuo," said Lu, "the amount of natural gas was too small, so the project was abandoned."
RSS