Just Another Dam Argument
3 Gorges Dam, China
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
Douglas Luken
Geo361: Hydrology
Many state there is a difference between “Triggered” and “Induced”
Induced :
Is the significant change in load stress and/or pore
pressure, causing a substantial change in the crust
Triggered:
If the crust is previously close to a fault failure due
to natural processes, and only required a minor
change in load or pore pressure
In this presentation we will assume they are one in the same.
“…earthquakes occurring in the vicinity of artificial water reservoirs as
a consequence of impounding.”
(Gupta, Harsh K., 2002.)
Depth of the water is the most significant factor (Volume is also a sig. factor)
One characteristic of RIS is that the magnitude of the foreshock is higher
than the magnitude of the aftershock and both values are generally higher
than in cases of natural earthquakes (USGS, 2006)
RIS can be immediately noticed during filling periods of reservoirs, and
can also occur later in the life of the reservoir. Also occurs after a rapid
change in reservoir water level.
Monthly variation in reservoir water depth and seismic activity as recorded by
an analogue station near the dam wall
Original and Relocated EQ
Hypocentres
Original locations with error bars,
shown (a) in map view and (b) in
cross section.
Relocated EQs, with their
much reduced error bars, (c)
in map form and (d) in cross
section.
The shaded area of the map is the Au Reservoir.
Hoover Dam
• Completed in 1935
• 100’s of Earthquakes occurred
as the water rose to its peak
height of 475ft in 1939
Konya, India
• Completed in 1963
• M ≥6.3 Earthquake in 1967
Three Gorges Dam
• Main Body Completed 2006
• 7661ft long • 1045km² surface area
Dam Height (m)
Impounding Began
Largest
EQ
Magnitude
China
154
2004
2008
7.9
Koya
India
103
1962
1967
6.3
Kariba
Zambia
128
1958
1963
6.2
Kremasta
Greece
160
1965
1966
6.2
Xinfengjiang
China
105
1959
1962
6.1
Srinakharin
Thailand
140
1977
1983
5.9
Marathon
Greece
67
1929
1938
5.7
Oroville
USA
236
1967
1975
5.7
Aswan
Eygpt
111
1964
1981
5.6
Benmore
New Zealand
110
1964
1966
5
Eucumbene
Australia
116
1957
1959
5
Hoover
USA
221
1935
1939
5
Bamjina
Yugoslavia
90
1966
1967
4.5-5.0
Bhasta
India
88
1981
1983
4.9
Kerr
USA
60
1958
1971
4.9
Kurobe
Japan
186
1960
1961
4.9
Monteyard
France
155
1962
1963
4.9
Shenwo
China
50
1972
1974
4.8
Akosombo
Ghana
134
1964
1964
4.7
Canelles
Spain
150
1960
1962
4.7
Dam
Zipingpu
Country
Reported Cases of RIS with M ≥ 4.0
*Source T.Valdut, Enviromental Aspects of Reservoir Induced Seismicity, May 1993
• Up to 2008, there were 96 large dam sites that had reported RIS
• 5 sites with a M ≥ 6.0
• 10 with M 5.0 – 5.9
~ These include China, Zambia,
India and Greece
• 28 with M 4.0 – 4.9
• 53 with M < 4.0
Others reported but not
included, due to lack of proper
equipment primarily in 3rd
world countries
RIS is a under-funded and often neglected field of research. The increase
in government support for monitoring stations and research for dams
worldwide.
Earthquake hazard assessments done as part of the dam design process
Better monitoring of seismic activity during impoundment, change or
possible reverse filling procedures done if RIS is detected, and model the
changes to pore pressure and mechanics underground.
Open disclosure of RIS occurrences during the initial impounding
There is resistance in the engineering community globally to accept the
significant or even existence of RIS.
There is no correlation to properly demonstrate between
earthquakes and reservoirs
If the natural seismicity is low, the danger of RIS is low as well.
No dam has yet to fail disastrously due to RIS, and the
dangers are being over exaggerated