An anecdote from the ancient Chinese book Liezi tells a story about a man from the state of Qi who was so obsessed with the thought that the sky might fall that he had no appetite for food nor could sleep well.

Recently some people have developed a similar anxiety over a hypothesis no less catastrophic to mankind. And the threat lies beneath our feet.

Xu Xiangyu, a 6-grader at Beijing No 2 Experimental Primary School, cried out "2012" when he first heard about the Chile earthquake, associating it at once with the Hollywood movie, which depicts a doomsday-like situation caused by strong earthquakes.

And his worry is by no means unfounded.

Extreme weather has been reported this winter in many places around the world: blizzards in Northern Europe, America and Asia, heat waves in South America and Australia, heavy snows in North China and severe droughts in the South. Now, Chile has been hit by a massive earthquake registered 8.8 on the Richter scale, less than two months after the devastating Haiti quake of 7.3 magnitude claimed nearly 290,000 lives.

Sun Shihong, a senior researcher with CEA China Earthquake Networks Center (CENC), said the world did look like it was entering a new phase of earthquake activity. The latest movements of the earth's crust undoubtedly demonstrated an "active state." "They are not abnormal, though. The earth has its life cycle, guided by it own rules," he said.

Sun, a chief forecaster with CENC before retiring in October 2008, has been closely observing earthquake trends.

The Haiti and Chile earthquakes were related, Sun believed. "In terms of earthquakes, the world seems to have entered a new phase. It may have started in late 2004 when a 6.4-magnitude earthquake rocked the eastern part of Indonesia," he said.

According to Sun, the world experienced an active quake phase from 1900 to 1964, when several strong quakes wrecked havoc. The following 40 or so years were relatively inactive.

The intensity of the latest earthquake in Chile was about 272 times that of the Haiti quake, yet it caused less damages. As Sun explained, the epicenter of the Chile quake was 60 km under ground, while the depth of the Haiti quake epicenter was 10 km. Probably for this reason as well, the Chile quake did not cause many related disasters such as tsunamis, volcanic eruptions, or landslides.

Likewise, the Chile quake's epicenter was about 300 km away from the country's capital Santiago and more than 100 km from the second largest city Concepcion, whereas the Haiti quake's epicenter was only 16 km from Haiti's capital Port au Prince.

Chile is a quake-prone country. The 9.5 magnitude earthquake that hit the country in 1960 was probably the most powerful one recorded in human history. Better prepared for such occurrences, Chile has constructed its buildings according to high anti-quake standards.

Forecasting earthquake trends is always very difficult as there are not many precedents on record for comparison. Besides, earlier events are often misleading if one tries to draw conclusions from them. The earth is very complicated and an earthquake seldom happens exactly where one has happened before. Human beings are still largely in the dark about how to predict them.

China has a rich record of earthquakes going back 600 years. Earthquakes of varied intensity occurred frequently for 250 years and 195 years respectively in Shanxi and Hebei Province. Nonetheless, Chinese researchers cannot forecast when the next big quake will hit.

Sun said he did not usually take predictions of doomsday seriously. "Many of these people do have a rich knowledge of astronomy or geography. They may be able to make accurate predictions of certain celestial phenomena. But the conclusions they draw are often far-fetched and serve particular purposes. Such predictions should not be trusted," Sun warned.

However, such wild predictions may serve as a good reminder of the danger that humanity faces on its path of development, especially when irresponsible human behavior has a growing negative impact on the environment. Frightening predictions may help raise awareness and draw attention to the problems, prompting us to take serious actions, Sun said.

As a true scientist, Sun believed in discussion and debate. He based his judgment on evidence and reasoning and rejected the notion that recent earthquakes were a premonition to imminent human catastrophe.

"The earth has a life cycle too. The late renowned Chinese geologist Li Siguang proposed that the earth is rotating slower than it was some 3 billion years ago," he said.

Frequent earthquakes in the last few years suggest the world has entered a new era of earth crust movement. How long this new phase will last and when and where the next strong quake will be are difficult to say. "But it seems to follow its own course, a normal cycle," Sun said.