Are we making earthquakes worse ?

Are dams at risk ?Last month the French magazine Science et Vie [Fr] dedicated a series of articles to the earthquake risks induced by dams, mines, oil drilling and geothermal power. You might think that these activities are without seismic risk.

But to their findings, around 200 earthquakes have been triggered by human activities so far. This can be explained by the billion of tonnes of coal, oil and minerals we have extracted so far.

This means that at least four energy sources – and two among the cleanest – are making earthquakes more frequent and more damaging.

Among the 200 earthquakes above mentioned, ten were above five of magnitude. Out of these ten, five were triggered by dams: Koyna, India in 1967 ; Srinagarind, Thailand in 1959 ; Hsinfengkiang in 1962 ; Kariba in Zambia in 1963 and finally Kremasta in Greece in 1966.

Art McGarr, a U.S. Geological Survey specialist stated in Science et Vie that there is a direct relation between the size of the activity and the magnitude of the earthquake.

Furthermore, researches carried out by Christian Klose, a geophysical hazards research scientist from Columbia University in New York, show that the Zipingpu dam reservoir may have triggered the Sichuan earthquake.

Wired Science published an interesting article that corroborates the findings of Science et Vie:

Some human actions can trigger much larger quakes along natural fault lines. That’s because humans, with the aid of our massive machines, can sling enough mass around to shift the pattern of stresses in the Earth’s crust.

Faults that might not have caused an earthquake for a million years can suddenly be pushed to failure, as Klose argues occurred during Australia’s only fatal earthquake in 1989. After the jump, we present the top five ways to create an earthquake.

Dams:

Water is heavier than air, so when the valley behind a dam is filled, the crust underneath the water experiences a massive change in stress load. For example, the Hoover Dam area experienced hundreds of quakes as Lake Mead filled. University of Alaska seismologist Larry Gedney explained, “Since [the dam] reached its peak of 475 feet in 1939, the level of seismicity has fluctuated in direct response to water level.

None of the shocks has been particularly damaging — the large