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Earthquakes (mostly between mangitude 3 and 4) may be caused by human activity

A strong earthquake 2004 in the Indian Ocean caused damage still in Chennai in China. Photo: Wikimedia Commons

The HiQuake database collects geological events related to anthropogenic activity which is often just the final straw that releases built-up stress

Some scientists say that the melting of the glaciers due to climate change may cause earthquakes as pressure on mountains is released and they lift up. These days a database for geological events triggered by human activity informed about its content. Its name is HiQuake (Human-induced earthquakes) and it includes approximately 730 entries, according to a report published in the „Data Mine“ column of the journal Seismological Research Letters.

The projects extend back almost 150 years, with most maximum observed magnitude earthquakes falling between magnitude 3 and 4. Above a strength of 7 buildings are destroyed.

The largest proposed human induced earthquake in the database is the 2008 magnitude 7.9 Wenchuan earthquake that occurred in China in response to the impoundment of the Zipingpu Reservoir only a few kilometers away from the mainshock epicenter.

Mining projects (37%) and water impounded behind dams (23%) are the most commonly reported causes of induced earthquakes, but unconventional oil and gas extraction projects using hydraulic fracturing, are now a frequent addition to the database, said Miles Wilson, a geophysicist at Durham University working on the HiQuake research effort.

In many cases, e.g. hydraulic fracturing operation induces microseismicity because the rock is fractured. They may even reach unusual strength when thus new boreholes come together with pre-existing geological faults. „The anthropogenic activity is just the final straw that releases this built-up stress,“ Wilson says in respect of stronger events.

HiQuake was first developed in 2016 by a group of researchers from Durham and Newcastle Universities, who were funded by the Dutch oil and gas company Nederlandse Aardolie Maatschappij to review the full global extent of induced earthquakes.

To build the database, Wilson and his colleagues analyzed peer-reviewed literature, academic presentations, media articles, and industry and government reports for projects where scientific evidence suggests that the human activity was the cause of an earthquake sequence. Each entry in the database corresponds to a project, or phase of a project.

Causes for man-made earthquakes may also be nuclear explosions and the building of heavy skyscrapers.

„Additionally, mines may become larger, deeper, and more extensive, surface water reservoir impoundments more common, and buildings on larger scales could be built to meet a growing world population and resource demand,“ he said. „Perhaps one day a balance will need to be struck between earthquake hazard and resource demand.“

HiQuake

(18.10.2017, USA: 10.18.2017)