The discovery was made in April 2012 and was immediately followed by a 3D seismic survey.

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It has reimbursed him for a 3d seismic survey of the land, however.

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Likewise the engineers, survey ships and seismic rigs that oil firms need to find and produce new deposits are expensive right now.

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The U.S. Geological Survey said it detected seismic activity with a magnitude of 5.1, bigger than the seismic activity produced in North Korea's previous two blasts.

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The Wednesday night blast shook houses 50 miles away and measured as a 2.1-magnitude seismic event, according to the United States Geological Survey.

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The U.S. Geological Survey, the federal outfit that studies earthquakes, acknowledges that increased seismic activity coincides with wastewater injection.

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Seismic activity was detected in North Korea this evening that the United States Geological Survey registered as a 5.1 magnitude earthquake.

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