A powerful earthquake that has left nearly 600 people dead in the southwestern Chinese province of Yunnan could be linked to the large number of dams and reservoirs in the area, a seismology expert told RFA.
According to Yang Yong, a senior researcher in the seismology team at the Sichuan provincial land and mining bureau in Chengdu, the quake came just months after authorities in Yunnan's worst-hit Ludian county filled up a brand new 23 million cubic-meter (812 million cubic-foot) capacity reservoir.
"Looking at the location of the Zhaotong earthquake and the proximity of several reservoirs around it, there is a sense of coincidence," Yang said.
He cited a major dam-building program in the region, which had resulted in a number of new reservoirs, as well as several more under construction.
"[The earthquake] was just 10 kilometers [6.2 miles] from the Yueliangwan and Tianhuaban reservoirs, while there are at least three major hydroelectric projects on the river near Zhaotong," Yang said. "They have been filling them up, one after another."
"The dams at Xiluodu and Jiaba are very large indeed, and lie just four or five kilometers [2.5 to 3 miles] from the epicenter of the quake," he said.
Full probe call
While Yang said the coincidence may not necessarily indicate cause and effect, he called on Beijing to launch a full scientific probe into possible triggers for the disaster, and to step up monitoring of the nearby Jinshajiang reservoir.
Yang has previously said that the huge earthquake that devastated the southwestern province of Sichuan on May 12, 2008 could have been triggered by hydroelectric power projects in the area, echoing his colleague, chief engineer Fan Xiao.
Fan and Yang told reporters at the time that pressure from the water in reservoirs contributed to the break-up of the earth's crust along the fault line, a claim that has also been made by other international seismology experts.
Reservoir-triggered seismicity is the term used by experts to describe the triggering of earthquakes by the physical processes that accompany the filling of large reservoirs.
Harsh K. Gupta, a top international expert on the subject, defined this in 2002 as "earthquakes occurring in the vicinity of artificial water reservoirs as a consequence of impoundment [i.e., the collection and confining of water]."
According to Gupta, more than 90 earthquakes are known to have been triggered by the filling of water reservoirs, including the 1967 Koyna earthquake in India, which measured 6.3 on the Richter scale.
While not all engineers accept his views, the independent U.S. Commission on Large Dams has recommended that the link between dams and quakes should be considered for reservoirs deeper than 80-100 meters (262-328 feet).
Jiangsu-based environmental activist Wu Lihong said the ruling Chinese Communist Party has pursued an aggressive dam-building program in recent years, in a bid to meet soaring demand for power.
But he said hydroelectric power isn't a low-impact form of energy.
"Hydroelectric power stations can cause seismological instability, triggering mudslides and all sorts of negative effects downstream," Wu said.
"All of these issues need to be taken into account."
The death toll from Sunday's 6.1 magnitude quake rose to nearly 600 on Wednesday after relief work led by the People's Liberation Army (PLA) was hampered by blocked roads and torrential rain.
At least 589 people had been confirmed killed by Wednesday morning, China's ministry of civil affairs said in a statement on its official website.
A further 2,401 people were injured, after more than 80,000 homes had collapsed to some degree, it said.
Rescuers have been steadily pulling corpses from the wreckage in areas they have been able to reach, while survivors are living outside under makeshift shelters or tents brought in with relief supplies.
A resident of worst-hit Longtoushan township surnamed Li said he knew of 51 people who had died in his home village of Babao alone, while a further 19 were still missing and many more had been injured.
"We have confirmed 51 deaths so far in our village...while more than 30 people have injuries, although most of them are light injuries," Li said.
He said three PLA army teams are currently probing the rubble and handing out relief supplies to survivors.
"An armed police unit including firefighters also showed up today," he said.
He said relief supplies of food had also begun to arrive in the region, where survivors had previously said they had subsisted for days after the quake with only the food they were able to dig out of the rubble.
"Relief supplies of several hundred packets of instant noodles arrived today, but that's only enough for half of the population," Li said.
"A packet of noodles can only last a person a day."
Villages cut off
Meanwhile, a Longtoushan resident surnamed Zhao said many more remote villages still remained cut off from rescue teams or relief supplies.
"Most of the victims here are relatively secure now, and they started to get what they needed [on Tuesday] afternoon," Zhao said.
"But there are still places that haven't been reached by rescue teams yet because the roads have been blocked and there's no way to get through."
And a resident of Shuimo township said the region is still being shaken by aftershocks.
"There were several today, and the roads are very slippery after the rains, so it's very hard for the trucks carrying supplies to get through," he said.
"The local drivers know the area better and are more skilled, so some stuff has got through, but most people can't," he added.
An official who answered the phone at the Ludian county government offices on Wednesday declined to comment.
"All the movements of relief supplies are being coordinated centrally by the [disaster relief center]," the official said.
Reported by Gao Shan and Yang Fan for RFA's Mandarin Service, and by Wen Yuqing for the Cantonese Service. Translated and written in English by Luisetta Mudie.