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.”