In the past decade there has been a remarkable increase in earthquake activity in the U.S.A. A U.S. Geological Survey research team says that these earthquakes are "almost certainly man-made."
Researchers for the U.S. Geological Survey have presented a study which states that natural gas and oil extraction activity has most likely provoked the series of recent earthquakes in the U.S.A, from Alabama through to the Northern Rocky Mountains.
They have not yet estimated a direct cause-effect relationship between gas and oil activity and earthquakes.
However, William Ellsworth, leader of the research team has said that the frequency of earthquakes increased in 2001 across a broad area of the country between Montana and Alabama and has culminated “in a 6-fold increase over 20th century levels in 2011.”
An abstract for USGS study, published by the Seismological Society of America, has stated that “It remains to be determined how they are related to either changes in extraction methodologies or the rate of oil and gas production.”
However, they can offer a possible explanation for this activity. They state that drilling requires the disposal of millions of gallons of waste water for each well, which could be a cause of the earthquake activity, and that the number of wells has increased dramatically over the past 10 years.
With the recent earthquakes in north-eastern Ohio, especially the largest which occurred on New Year´s Eve, the Department of Natural Resources has closed or suspended developments by natural gas drillers of 5 deep waste water disposal wells. This closure or suspension will be in effect until an investigation into well impact on increased seismic activity can be completed in the area.
Other states are investigating so-called injection wells, including Arkansas, where a permanent moratorium on disposal wells has been imposed over an approximate 1,200-square-mile area. This is due to enhanced seismic activity near the Fayetteville Shale.
The study says: “The acceleration in activity that began in 2009 appears to involve a combination of source regions of oil and gas production, including the Guy, Arkansas, region, and in central and southern Oklahoma. Horton, et al. (2012) provided strong evidence linking the Guy, AK, activity to deep waste water injection wells,”
According to the Federal Energy Information Administration, shale gas production has grown on average, from 2006 to 2010, by nearly 50%.