The injection of wastewater from underground operations such as oil drilling is known to increase local seismic activity.
Now a study in Science http://www.sciencemag.org/content/341/6142/164.abstract suggests that waves from the most distant temblors can cause quakes at wastewater sites.
Researchers suggest this can act as a kind of "stress meter" for the sites.
The notion of natural earthquake triggering is not new; in hydrothermal and volcanic areas, tremors can be triggered by large, distant earthquakes. But the new study suggests what is in effect a new category: natural triggering of seismic events primed by human activity.
Injection of wastewater from operations such as drilling, geothermal, or hydraulic fracturing ("fracking") is banned in the UK and many European countries, but it has become increasingly prevalent in the US.
In the state of Texas alone, more than 7,000 such wells are in operation and the link between injection wells and even large seismic events is strengthening...."
'...Richard Davies, http://www.dur.ac.uk/earth.sciences/staff/?id=3355 director of the Durham Energy Institute at the University of Durham, called the paper "an exciting, interesting result".
"Seismologists have known for some time that there are transient stresses from earthquakes that can potentially cause other faults to slip, causing an earthquake," Prof Davies told BBC News.
"But this paper is a very interesting contribution, as it proposes that mankind can artificially 'prime the faults' by injecting wastewater over long periods under the ground.
"Mankind is essentially lubricating the faults enough so that they are eventually triggered by a distant, natural earthquake. Think of a hovercraft - the air pumped into the base of the craft means that even small forces allow the heavy vehicle to move - the physics is the same."..."