(December 12, 2012) A new study published by Probe International reveals a dangerous relationship between dam reservoirs and seismic activity.
The Chinese earthquake that killed 80,000 people in May of 2008 most likely was not an act of God, a study released today has found. Rather, the culprit was probably a nearby hydro-electric dam whose construction and operation triggered one of the world’s worst disasters of the century.
The study by Fan Xiao, a Chinese geologist and chief engineer of the Regional Geological Survey Team of the Sichuan Geology and Mineral Bureau, arrived at this conclusion after an analysis of some 60 studies of the earthquake, conducted between 2008 and 2012.
In the aftermath of the deadly Sichuan-area, Wenchuan earthquake, many scientists suspected the Zipingpu Dam of causing the quake. Chinese authorities denied it, saying that the epicentre of the quake was too deep and on an unrelated fault and, therefore, not a case of reservoir-induced seismicity.
But Chinese authorities appear to have been wrong on both counts, says Mr. Fan.
“The mounting body of evidence and analysis indicates that the magnitude 8 earthquake was triggered by the mass loading and increased pore pressure caused by the Zipingpu reservoir,” he says.
This would make the May 2008 earthquake far and away the largest case of reservoir-
induced seismicity (RIS) on record. Until Zipingpu, the most powerful RIS event on record was a 6.5M earthquake that struck in 1967, at the site of India’s Koyna Dam.
After the May 12, 2008 earthquake in Wenchuan, Sichuan, suspicion grew among Earth scientists that the Zipingpu Dam reservoir had triggered the devastating earthquake, which killed more than 80,000 Chinese citizens. Since then, some 50 to 60 articles and studies have investigated this massive seismic event and its relationship to the Zipingpu reservoir. This paper reviews the literature and concludes that the mounting body of evidence and analysis indicates that the magnitude 8 earthquake was triggered by the mass loading and increased pore pressure caused by the Zipingpu reservoir. It also concludes that the initial seismogenic rupture of the Wenchuan earthquake did not occur along the Yingxiu Fault Belt at a depth of 14 to 19 kilometres, as previously thought, but at a depth of 6 to 9 km along the Shuimo-Miaoziping Fault Belt, which passes underneath the Zipingpu reservoir.
This initial seismogenic rupture subsequently expanded and spread in a series of rupture events that were closely linked to each other for 90 seconds along the Longmenshan Central Fault, moving 200-300 km from southwest to northeast. The near absence of a typical precursor before the Wenchuan earthquake, in addition to seismic recordings of abnormal, small earthquakes in the reservoir area as early as April 5, 2008, suggest that this was not a conventional case of reservoir-induced seismicity (RIS) in which the accumulation of stress in a fault zone is nearing the critical point, and the impounding activities of a reservoir merely trigger the inevitable seismic event.
Rather, the new findings suggest that the filling and drawdown of the Zipingpu reservoir triggered clusters of small earthquakes which caused new ruptures in the rock that, in turn, altered the stress field in the Longmenshan region and led to an accelerating release of energy. This series of events culminated in the giant rupture that became the MS8.0 Wenchuan earthquake.
In light of these findings, Earth scientists and decision-makers alike must now address a dangerous new reality: if reservoir-induced seismicity can be considered human-induced foreshocks to a major earthquake, then the science of reservoir-induced seismicity must consider the possibility that reservoirs can trigger unanticipated tectonic activity. Most urgently, the findings presented in this paper about the Wenchuan earthquake make a review of current plans to build dozens of large dams with accompanying large reservoirs, in and near areas of high regional tectonic stress in western China, a high priority.
For more information, contact:
Patricia Adams, Executive Director, Probe International
Tel. 1 (416) 964-9223 (ext. 227)
For Fan Xiao, email: firstname.lastname@example.org
Read the English translation of Fan Xiao’s study here.
Read the original Chinese version of Fan Xiao’s study here.
For news coverage of the study’s release:
Engineer: Hydroelectric Dam Linked to 2008 Sichuan Quake
New Tang Dynasty Television, Dec. 19, 2012
[Study author] Fan Xiao says that the link between Zipingpu Dam and the 2008 Sichuan earthquake should serve as a warning to officials to reassess the current plans of dam construction.
2008 Sichuan Earthquake Likely Man-Made
China Digital Times, Dec. 14, 2012
A new study published by Probe International, based on around 60 other studies of the 2008 Sichuan earthquake, backs earlier arguments that the disaster was caused by the weight of the Zipingpu dam reservoir. The authors suggest that extensive plans for further hydropower projects in vulnerable regions should be urgently reconsidered.
China’s 2008 Sichuan Earthquake Was Man-Made
Softpedia.com, Dec. 13, 2012
According to a new report made public by Probe International, China’s Sichuan earthquake (i.e. the one that killed roughly 80,000 people on May 12, 2008) was man-made.