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The Warsaw Voice » Society » March 31, 2015
Institute of Geophysics Polish Academy of Science
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Induced Seismicity
March 31, 2015   
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Polish scientists will soon manage an integrated European database of induced seismicity and coordinate the work of researchers from 16 countries taking part in the European Plate Observing System (EPOS), Europe’s biggest infrastructure project in Earth sciences. The management center will be set up in Cracow.

“This is the first time ever that a country from the new Europe—the countries that joined the European Union just under 11 years ago—has been appointed a leader of a large European research project of this kind,” says Prof. StanisławLasocki, head of the Department of Seismology of the Cracow-based Institute of Geophysics, part of the Polish Academy of Sciences. The EPOS program, launched in 2010, will continue until 2040.

The Department of Seismology deals with observational seismology in two different areas: earthquakes (natural seismic events) and induced (anthropogenic) seismicity. The latter is seismic activity caused by humans, chiefly the mining of natural resources. It is caused by underground mines, geothermal energy facilities, both conventional and unconventional extraction of hydrocarbons (crude oil and natural gas), underground storage of liquids or gases and other technological activities. Filling tanks linked to hydroelectric power plants or water dams can also cause effects that trigger the natural tendency of rock to crack. Sequestration of carbon dioxide looks set to be another major problem in the future.

The first case that can be described as induced seismicity dates back to the 18th century. The case in question was described in English historical records and concerned a mine. Sometimes human activity is only the trigger, initiating a process that could have eventually occurred naturally in a rock formation over dozens or hundreds of thousands of years.

The scale of induced seismic events ranges from very small incidents to the force of natural earthquakes. A tragedy in China in 2008 when at least 70,000 people were killed after an earthquake of a magnitude of 7 on the Richter scale may have been—the debate here is still ongoing—triggered by human activity. Earthquakes in Italy in the Emilia Romagna region in 2012, the most costly ever in Europe, were likely triggered by oil and gas mining.

Natural earthquakes are disasters stemming from the nature of the dynamics of the Earth’s interior and humans have no influence over them. They can only try to predict them (still a rather distant prospect) and use construction methods in endangered regions that prevent the destruction of buildings. Induced seismicity, on the other hand, is caused by human activity and here—at least theoretically—the danger can be reduced.

“A sensible compromise is needed between essential human industrial activity and environmental protection,” says Lasocki. “Induced seismicity is a field of conflict. On one side you have those who focus on the economy, on production, while on the other you have those who want things to stay calm. Between them are we, the scientists, whose task is to bring about accord,” he adds.

According to Lasocki, Europeans have become a little oversensitive regarding the impact of industrial activity on people and the environment. One prominent example was a small tremor in the northern Swiss city of Basel in 2006 that caused little damage but immediately resulted in a local geothermal well being shut down. The project had cost 50 million euros. The tremor put in question the entire future of geothermal energy in Europe. Germany also started closing down geothermal wells. A tremor of a magnitude of 2.3 that occurred in Blackpool, northeast England, put in question shale gas extraction in Europe.

“It’s become popular to scare people. That’s why our role is to offer reliable information on possible dangers while monitoring industry so that it does not try risky projects using hazardous technologies in a given area,” says Lasocki.

One type of work carried out by the Department of Seismology is research. Experts observe different phenomena of interest to them without any interference from possible customers expecting simple answers. Such research is financed with public funds.

Another area of work involves studies and projects for commercial customers. One example is a project that has been conducted for 12 years for the Hydrotechnical Unit of copper giant KGHM Polska MiedĽ. The project involves periodical studies of seismic hazards in Europe’s biggest post-flotation mineral waste repository, ŻelaznyMost, in southern Poland. If its embankment were damaged as a result of a seismic tremor, an environmental disaster of an unbelievable scale would ensue.

“We don’t accept invitations regarding very short-term projects or those not requiring expertise; we aim to operate on a higher level, where strictly scientific work is required,” Lasocki says.

The time span of hazard assessments is usually determined by the period over which industrial activity will be conducted in a given area. This can vary from months in the case of a local seismic process, to a dozen or more years when the overall induced seismicity in a particular region is to be taken into account. Seismic events that are not induced but triggered by human activity are a completely different matter: studies of this phenomenon have to cover entire geological eras and natural processes that have to be investigated in order to assess to what extent human activity can change them, speeding up the occurrence of a possible disaster.
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