Since 2009, significant increases in earthquake activity, particularly in the central and eastern United States, have led scientists to study the ways some earthquakes may be induced by industrial operations and other manmade practices.
Particularly, quakes that are associated with wastewater disposal wells, as well as gas extraction processes that are now widely employed, have been given special consideration in relation to the sudden upturn in earthquakes.
According to a new report released on Thursday by the U.S. Geological Survey, a new study outlines a set of preliminary models for use in predicting the hazards of quakes associated with increases in seismicity.
According to the USGS website:
USGS scientists identified 17 areas within eight states with increased rates of induced seismicity. Since 2000, several of these areas have experienced high levels of seismicity, with substantial increases since 2009 that continue today. This is the first comprehensive assessment of the hazard levels associated with induced earthquakes in these areas. A detailed list of these areas is provided in the accompanying map, including the states of Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma, and Texas.
Scientists developed the models by analyzing earthquakes in these zones and considering their rates, locations, maximum magnitude, and ground motions.
Mark Petersen, Chief of the USGS National Seismic Hazard Modeling Project, notes that, “This new report describes for the first time how injection-induced earthquakes can be incorporated into U.S. seismic hazard maps… these earthquakes are occurring at a higher rate than ever before and pose a much greater risk to people living nearby.” The scope of the study is aimed at helping assist in precautionary measures leading up to possible future quakes in the regions outlined within the study.
In November 2014, the Oklahoma Geological Survey hosted a joint workshop with the USGS, where new seismic data from Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma and Texas were examined. Much of the findings in the present study were sourced from this workshop.
Throughout 2014, a number of loud booms were reported throughout the Midwest and northeastern United States. Among the states that were the focus of the present USGS study, Kansas, Ohio, and Oklahoma experienced a number of reports of loud booms of unexplained origin, which some have speculated to be associated with hydraulic fracturing (otherwise known as “fracking”).
According to the new USGS data, in addition to quakes associated with such industrial activities, it may be possible that some of the mystery booms reported in various locals throughout the U.S. are somehow related. In the past, loud booms have occasionally been reported prior to or during earthquakes; examples include reports of booms that preceded the Great 1906 San Francisco Earthquake, and noises that accompanied the New Madrid quakes of 1811 and 1812 that were likened to “sounds of distant thunder and loud explosions.” However, the current USGS report does not specifically reference sounds associated with induced seismic activity.
Regarding the use of such terms as “induced seismicity,” the authors note, “We acknowledge that this classification is based on circumstantial evidence and scientific judgment. Difficulties in assessing seismic hazard arise from a lack of relevant technical information on human industrial activity (that is, pumping data for injection wells). Thus, in this report we do not explore the causes of the increased seismicity, but rather try to find a way to quantify the associated hazard.”
The report can be read online in its entirety at the USGS website.