A British seismologist has suggested the recent series of earthquakes in Surrey had no causal link to oil drilling activities being carried out in the region. Surrey Live quoted Dr. Richard Luckett from the British Geological Survey as saying, "The truth is we never knew the actual depth of the first earthquakes and we still don't actually know their depths."
Luckett's comment refers to the reported depth of the first series of earth tremors that shook Surrey a few months ago, and at the time, the BGS said they originated at about 1 kilometer underground, which is the depth at which oil and gas exploration drilling is being done.
The most recent data from the county has revealed that the last series of quakes, from September 28, originated at depths of 2.1 kilometers. The data was gathered by seismographs.
"We put the stations in to be able to measure the depths more accurately because the depths of the first ones were measured with an error margin of plus or minus 5 km," Dr. Luckett told the regional news outlet, adding that the latest seismograph data had an error margin of 200 meters, which meant there was no way the quakes had originated at the depth of oil and gas drilling, that is, 1 kilometer.
In early July, Surrey was hit by three earthquakes over two weeks. Since Surrey is not a quake zone and tremors there are far from frequent, a concern about a possible link between oil and gas exploration and the quakes was not surprising.
At the time, the British Geological Survey said in a statement, as carried by The Independent, that "We are unable to say categorically if these earthquakes are related to hydrocarbon exploration or production in the Weald, mainly because of the uncertainties in our estimates of the earthquake epicentres and depths."
The statement noted, "While it is well known that hydrocarbon exploration and production can result in manmade or 'induced' earthquakes, such events usually result from either long term hydrocarbon extraction, or the injection of fluids (eg hydraulic fracturing) during production." The latter has also been the conclusion of the U.S. Geological Survey.
By Irina Slav for Oilprice.com
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Irina is a writer for Oilprice.com with over a decade of experience writing on the oil and gas industry. More