PGS: Leith on fracking

The November, 2012, meeting of the Potomac Geophysical Society will be held November 15th at the Fort Myer Officers’ Club in Arlington, VA ( in the Glassed-in room in the Fife and Drum (main dining room).

Abstract:  To produce natural gas from shale formations, it is necessary to increase the interconnectedness of the pore space (permeability) so that the gas can flow through the rock mass and be extracted through production wells. This is usually done by hydraulic fracturing (“fracking”).  In addition to natural gas, fracking fluids and formation waters are returned to the surface. This wastewater is often disposed of by injection into deep wells. The injection of wastewater deep into the subsurface can cause earthquakes that are large enough to be felt and may cause damage.  Only in very rare cases does fracking cause small earthquakes, but they are almost always too small to be a safety concern.  Of more than 150,000 Class II injection wells in the United States, roughly 40,000 are waste fluid disposal wells from oil and gas operations.  Only a small fraction of these disposal wells have induced earthquakes that are large enough to be of concern to the public.  Of the case histories for which there is a scientific consensus that an injection operation induced earthquakes, the largest are just above magnitude 5. USGS scientists have investigated a recent sharp increase in the number of magnitude 3 and larger earthquakes in the midcontinent of the United States. These earthquakes are large enough to be felt by many people but are small enough that they rarely cause damage.  The average number of earthquakes occurring per year of M3 or greater increased starting in 2001, culminating in 2008-2011 with a six-fold increase over 20th century levels.  Nearly half of these earthquakes are occurring in areas where hydraulic fracturing, and hence wastewater disposal, is known to be occurring.

BIO:  William Leith, Ph.D. is the Senior Science Advisor for Earthquake and Geologic Hazards at the U. S. Geological Survey.  In this position, he oversees the Earthquake Hazards, Geomagnetism and Global Seismographic Network Programs.  Bill joined the USGS in 1986, after receiving a doctoral degree in seismology and geology from Columbia University, and a bachelor’s degree from the University of California at Berkeley. He served USGS as Chief of the USGS Special Geologic Studies Group from 1990-2001, as Senior Technical Advisor to the Assistant Secretary of State for Verification and Compliance, from 2001-2003, as the Coordinator of the Advanced National Seismic System from 2003-2012, and as USGS Acting Associate Director in 2010-2011.  Bill has over 100 publications in the areas of seismology, geology, engineering geology, tectonics, and the applications of these subjects to earthquake safety, response and engineering, as well as to nuclear weapons testing and test monitoring, treaty verification and compliance assessments.

Meeting Room and Dining Arrangements: We now meet in the glassed-in room at the back of the main dining room—The Fife and Drum. We order individually from the Club menu, which has a nice variety of dinner offerings. We pay a single bill (I pay it with my Officers Club credit card), so we collect at least $25 from each diner with the agreement, that if one orders more than $20 in food and drink, he adds the amount over $20 to his contribution. The $5 overcharge goes to the Room Fee, Tax, Gratuity, and the Speaker’s Dinner. We collect on the Honor System. We did this throughout the last year, and it worked well. This room change and use of the menu have greatly reduced the loss that we have incurred in the past for having fewer than 20 people dining, and the change has preserved the viability of using the Officers Club for our meetings.

Reception at 6:00. Order Dinner at 7:00. Talk at 8:30 PM. Please note that the meal orders will be taken at 7:00. Allow 15 minutes for security entering Ft. Myer as all civilian vehicles are searched. To ensure access to and from Fort Myer use the Hatfield Gate, open 24 hours a day ( Reservations are not necessary, however, we need a head count, so, if you wish to attend dinner ($25), please inform Bob Fraser at 540-888-3001 or via E-mail at you wish, please feel free to attend the talk without dinner. Non-members and guests are welcome. Visit the PGS web site at for new meeting announcements, etc. Please send changes of address or email


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