China's Dams

Yunnan earthquake linked to dam-building, says Chinese geologist

The 6.5-magnitude earthquake that devastated southwestern China’s Yunnan Province on August 3 and killed nearly 600 is linked to the world’s largest and most intensive dam-building scheme on the Jinsha River, says renowned, independent geologist-explorer, Yang Yong.

Probe International contributor, Yang Yong, has spent 30 years traveling and studying the Qinghai-Tibet Plateau. He is the Chairman and Chief Scientist of Heng Duan Shan Society (an environmental organization that independently assesses river developments in China) and Vice Director of Expert Committee of China Foundation for Desertification Control.

Probe International will soon publish a report by Yang on the potential threat posed by a cascade of hydro­dams proposed for the Jinsha River in an area already extremely vulnerable to destabilizing geological events and seismic activity. The environmental implications of dam-building become much more complicated and severe in the advent of a powerful earthquake should one strike the Jinsha region and cause the river to become blocked, says Yang; placing nearby densely populated areas at risk and increasing the possibility of dam failure, flooding, secondary disasters, among other scenarios. The impounding activities of reservoirs along the Jinsha at almost every 100 km in a cascade pattern could also trigger reservoir­ induced seismicity (RIS), cause man­made river damming events, and revive dormant geological threats.

By Liu Qin, published by China Dialogue on August 20, 2014

Liu Qin (LQ): What evidence is there linking the Ludian earthquake with hydropower development?

Yang Yong (YY): Currently we just need to take the basic facts seriously – the epicentre of the latest Ludian earthquake was in the Niulan River valley, and the Niulan is a tributary to the Jinsha. It was less than 7 kilometres away from Tianhuaban, the seventh dam in the Niulan cascade and just 10 kilometres from the Xiluodu Dam on the Jinsha, the westernmost tributary to the Yangtze.

The epicentre of the September 2012 Yiliang earthquake was less than 10 kilometres from the Malin Dam on the Luoze River, which was built in 2011; and less than 60 kilometres from the Xiangjiaba Dam on the Jinsha.

The Yongshan earthquake in April 2014 was less than 7 kilometres from the Xiluodu Dam on the Jinsha.

The time and location of these earthquakes link with the times the reservoirs at Xiangjiaba and Xiluodu on the Jinsha, and Tianhuaban on the Niulan, were being filled.

LQ: The Jinsha basin is in China’s most active geological zone, and one of the world’s most active. What are the risks of building huge dams and reservoirs here?

YY: Intensive hydropower here involves two types of geological risk: First, a strong earthquake near these facilities can cause major damage and spark off secondary disasters.

The Jinsha and its tributaries flow through the Sichuan-Yunnan fault zone, with some stretches of the river running parallel to or along the fault lines. The area is one of high mountain valleys, with fragmented geology and many unstable cliffs.

Second, the region’s complex and active geology means reservoirs behind the dams will spark stronger and more frequent earthquakes.

Recent years have seen a period of geological activity. There would be earthquakes here even if it wasn’t for the dam reservoirs. But, the reservoirs may result in more powerful levels of stress. Scientists still don’t fully understand those processes, and we can’t understand or control them.

Construction plans for hydropower dams in the Hengduan Mountains [on the Yunnan-Sichuan border] have overlooked how rivers can become blocked in such geologically active zones.

Given the history of earthquakes on the Jinsha, and based on my own research, let’s look at what might happen if there was an earthquake of magnitude 7 or 8 on the Jinsha.

Risks include multiple landslides upstream at the Tongjia Gorge, forming two or three barrier lakes. Hillsides on the Batang-Benzilan River stretch could collapse, making many old landslide sites active again and forming a string of barrier lakes. The generators and transmission equipment of hydropower plants would be badly damaged.

The river would be blocked again at Tiger Leaping Gorge due to landslides, with transmission equipment at Ahai and Ludila badly damaged.

There may be further landslides at Wudongde downstream, with old landslide sites further downstream becoming active again. Blockages could cause river water to back up towards the dam, with generating equipment and buildings badly damaged by landslides.

There could also be a number of landslides at Xiluodu, with the dam severely tested by uncontrolled releases of water from other dams and barrier lakes.

LQ: Under what conditions does hydropower development give rise to earthquakes?

YY: It depends on the geology of the reservoir area, how those structures formed, the size of the reservoir, and how it is operated.

Read the full interview here on China Dialogue.

Related reading on large dams and seismic hazard

Impoundment of two mega-dams on China’s Jinsha River triggers earthquake in Ludian
Yunnan earthquake raises fears on hydropower projects
Yunnan earthquake linked to dam-building, says Chinese geologist
Impoundment of Jinping-I Dam on Yangtze tributary triggers quakes
On alert: RIS risk amid rash of earthquakes in China’s Sichuan-Yunnan region
Quake strikes Three Gorges Dam area again
More earthquakes strike Three Gorges Dam region
Are dams triggering China’s earthquakes?
Could dams be causing China’s earthquakes?
Aftershocks from Sichuan earthquake pose threat of secondary disasters
Sichuan earthquake may be aftershock of 2008 killer quake: Chinese geologist
Deadly earthquake in China may be aftershock of 2008 Wenchuan quake
On alert: RIS risk amid rash of earthquakes in China’s Sichuan-Yunnan region
Press Release: 80,000 deaths from 2008 Chinese earthquake was likely not an act of God, says new study
Mega-dams in China’s earthquake zones could have “disastrous consequences
Three Gorges Dam failing: Chinese dam increases risk of earthquakes
Hong Kong earthquake an aftershock triggered by Chinese dam 50 years ago

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