How Do Dams Trigger Earthquakes?

According to scientists, earthquakes are triggered by dams, since there are many cases giving evidence that the earthquakes have been linked to the construction of dams.

Dr. V. P Jauhari in his paper "Reservoir-Induced Seismicity (RIS)" said "The most widely accepted explanation of how dams cause earthquakes is related to the extra water pressure created in the micro-cracks and fissures in the ground under and near a reservoir. When the pressure of the water in the rocks increases, it acts to lubricate faults which are already under tectonic strain, but are prevented from slipping by the friction of the rock surfaces."

There is a world of difference among dam sites due to their geological characteristics, which are unique for each and every of them. This means that it is very difficult to predict whether earthquakes will occur. However, as far as the International Commission on Large Dams is concerned, RIS should be considered for reservoirs that are deeper than 100 meters. 

New reservoirs could cause earthquakes due to the change in stress because of the weight of water, or by increased groundwater pore pressure that decreases the effective strength of the rock under the reservoir. The energy which is released is nothing but a normal tectonic strain energy that has been prematurely released because of the reservoir. It is known that ground water plays a large part in earthquake activity, because the normal stress within a rock is reduced by water pore pressure, while the shear stress remains stable.

Only if we were aware of the state of stress and the rock strength at earthquake depths, prediction of RIS could be done, but those factors cannot be measured directly.