PGS: Sumy on induced earthquakes

Please join us for the December 14, 2017 meeting of the Potomac Geophysical Society at 7:00 p.m. at DoubleTree by Hilton McLean Tysons, 1960 Chain Bridge Road, 22102.  This location is within one-half mile of the Tysons Corner Metro station, near I-495, and has free parking available.  Our private meeting room is located in the back of the Orchard Cafe restaurant on the second floor of the hotel. The optional dinner cost will be discounted to $30 for members in good standing (have paid dues) and students, and $40 for non-members, and is inclusive of iced tea, coffee, tax and gratuity. Members and guests may attend the presentation after dinner for no charge; we estimate that the presentation will begin at 8:15 p.m.  For attendees who arrive early, the social will be held in O’Malley’s Pub on the first floor of the DoubleTree by Hilton hotel.  Drinks may also be purchased in the private meeting room on a cash basis.

Social: 6:00-7:00 p.m. O’Malley’s Pub, first floor Crowne Plaza

Dinner: 7:00-8:15 p.m. Orchard Cafe, second floor Crowne Plaza

Meeting & Presentation: 8:15-9:30 p.m. Peachtree Room in the Orchard Cafe, second floor DoubleTree by Hilton

This Month’s Speaker:

Danielle Sumy, PhD

Induced Earthquakes: Past Lessons and Future Research Directions

Hydraulic fracturing, wastewater injection, reservoir impoundment, and geothermal activity, to name a few, are all known causes of induced earthquakes around the world. Small to moderate events in Ohio, Colorado, Texas, Arkansas, and Oklahoma have shed light on the induced earthquake issue in the central and eastern United States over the past decade. These earthquakes have been particularly newsworthy and well investigated, and have created debate amongst communities on how to best regulate the causes and mitigate the risk of earthquake activity. In this talk, I will provide a general overview on the history and mechanisms that induce earthquake activity, discuss my own research on the 2011 Prague, Oklahoma events and the research of others, and look forward to the future in the context of how these recent discoveries shape the dialogue between government regulators, community leaders, and the public.

Biography: Dr. Danielle Sumy earned her PhD from the Lamont-Doherty Earth Observatory at Columbia University in 2011 in marine geology and geophysics, where she specifically focused on the hydraulic mechanisms of earthquake activity at mid-ocean ridge hydrothermal systems. She brought that expertise to the subject of induced seismicity during her postdoctoral fellowships at the USGS in Pasadena, CA and at the University of Southern California. In 2014, she joined the IRIS Consortium, a National Science Foundation large facility that focuses on the operations and management of regional and global seismic networks and the storage of data from these networks, as well as education and outreach efforts to students, professionals, and the public


GSW 1524: Bentley on visualization in geology


Meeting Number 1524

John Wesley Powell Auditorium, Cosmos Club, 2170 Florida Ave NW Wednesday, December 6, 2017; Refreshments 7:30 pm; Meeting 8:00 pm




Callan Bentley, Northern Virginia Community College – Visualization in Geology: a brief history, best practices, & dispatches from the future.



Announcing the Slate of Officers for 2018; to be voted on at the Annual Meeting on December 6, 2017.

President:                     Karen Prestegaard (University of Maryland)

1st Vice President:       Michael Purucker (NASA)

2nd Vice President:     Ester Sztein (The National Academies)

Treasurer:                     Carl-Henry Geschwind (Independent Scholar)

Meeting Secretary:      Victor Zabielski (Northern Virginia Community College)

Council Secretary:        Pat Carr (National Geospatial Intelligence Agency)

Council Members (2018-2019):  Laura Helmuth (The Washington Post)

Libby Stern (federal government)

Mark McBride (Nuclear Regulatory Commission-retired)

Past-President:         Callan Bentley (Northern Virginia Community College)

Continuing Councilors:     Larry Meinert (USGS)

Michael Toomey (USGS)

Jessica Rodysill (USGS)


If you have not done so already, renew your 2018 GSW membership based on the e-mail reminders you have received.  We will need to print and mail paper notices by the end of December to those who have not renewed.


Future Meetings  2018: Jan 3; Feb 7; March 14; April 4, 18; May 2; Sept 12; Oct 3, 24; Nov 14; Dec 5 (Presidential address & annual meeting).

Know someone who would enjoy GSW? Consider inviting a colleague or friend to the meeting.

UMD: Boise State’s Kohn on Shear heating in subduction zones

2017 University of Maryland Geology Colloquium Series

Friday, November 17th 2017 at 3:00 pm
in PLS 1130, College Park campus

Matthew Kohn
Boise State University

Shear heating controls mineralogy, seismicity, and convection in subduction zones

Popular thermal-mechanical models of modern subduction systems are c. 300 °C colder at c. 50 km depth – the seismic-aseismic transition – than pressure-temperature conditions determined from exhumed metamorphic rocks, i.e. “Rocks are hotter than models” (Penniston-Dorland et al., 2015, EPSL). Subduction zone thermal structure is crucial for predicting depths of seismicity, fluid release, and sub-arc melting conditions. In this talk I will show that adding realistic shear stresses to thermal models quantitatively reproduces surface heat flow and the pressure-temperature conditions recorded by exhumed metamorphic rocks. A consistent seismic-aseismic transition depth of c. 50 km, however, is difficult to explain through mineralogical or thermal weakening mechanisms. Rather, I propose that mechanical removal of rheologically weak and buoyant rocks along the subduction interface leads to seismic decoupling and dynamic coupling bet! ween slab and mantle to drive mantle wedge convection and arc volcanism.

GSW 1524: Bentley on geological visualization

The 1524th meeting of the Geological Society of Washington will be on
Wednesday, December 6, 2017
featuring :

Presidential address

Visualization in Geology:
a brief history, best practices, & dispatches from the future

Stretched belemnite from the Alps
Callan Bentley, Northern Virginia Community College

(GSW’s 124th Annual Meeting to follow.)

Refreshments at 7:30 PM; Formal program at 8:00 PM
John Wesley Powell Auditorium, 2170 Florida Avenue NW, Washington, DC
(see here for directions)

AEG: Ground Vibration Control from Explosives Demolition of the Kosciuszko Bridge

Association of Environmental & Engineering Geologists

D.C. – Maryland – Virginia Chapter (

Thursday, November 16, 2017, from 5:30 PM to 7:45 PM
at Brewer’s Alley in Frederick, MD

AEG Members $40, Non-members $45 (includes dinner; student and retiree discounts available). Please RSVP by Monday, November 13, via email ( or via online payment (

Patrick T. Hastings, G.I.T. and David K. Miller, P.G.

Seismic Surveys, Inc.

Ground Vibration Control from Explosives Demolition of the Kosciuszko Bridge

The project involved designing and building the new eastbound structures of Interstate 278 over the Newtown Creek from Brooklyn to Queens, New York City, and the subsequent explosives felling of the existing Kosciuszko Bridge. The explosive demolition of the old Kosciuszko Bridge included 10 steel trusses on the Brooklyn approach and 10 steel trusses on the Queens approach. This presentation discusses the methods and procedures that were developed to protect third-party buildings, buried gas transmission pipelines, the Long Island Railroad, the Historical Old Calvary Cemetery and the new K-Bridges. During the explosive demolition on October 1, 2017, SSI used 52 seismographs at adjacent structures to monitor vibrations. The conclusion of the presentation will include a video compilation of Controlled Demolition, Inc. (CDI) successful explosives felling of the 3,104’ long, 20-span, structural steel, iconic Kosciuszko Bridge.

Please refer to our meeting announcement for full details (

UMD: Le Mével on volcanic unrest at large silicic systems

2017 University of Maryland Geology Colloquium Series

Friday, November 10th 2017 at 3:00 pm
in PLS 1130, UMD- College Park

Hélène Le Mével
DTM/Carnegie Institution for Science

Geodetic measurements and numerical models of volcanic unrest at large silicic systems.

I will examine the ground deformation associated to non-eruptive unrests at two volcanic systems: the Laguna del Maule volcanic field (Chile), experiencing high uplift rates since 2007, and the Long Valley caldera (USA), experiencing multiple episodes of surface uplift over the last 40 years. I will present results from analytical and numerical models to interpret these episodes of ground deformation in terms of magmatic processes.

Paleontological Society of Washington November seminar

The Paleontological Society of Washington

7:00 pm, Wednesday, November 15

National Museum of Natural History, Constitution Ave. entrance

An Amateur’s Collection of Corals from the North East DC Area

Christopher Hough

Member, Paleontological Society of Washington

From the Coastal Plain to the eastern edge of the Tectonic Plate(s) of Eastern North America, an amateur’s collection of marine invertebrate fossils tells an intriguing natural history that we all pass every day on our way to work. Taking advantage of the well –eroded stream beds of northeastern DC area and the foresight of the National Area Park and Planning Commission to preserve them as they are, I have collected a sampling of corals spanning the late Pre-Cambrian to the late Cretaceous. Though the collection is spotty from the perspective of diversity, it tells an interesting story of what went on during that time.

Non-Smithsonian visitors will be escorted from the Constitution Ave. entrance of the NMNH to the Q?rius auditorium at 6:50 and 6:55 p.m. Society members will host the speaker for dinner at the Elephant & Castle (1201 Pennsylvania Ave.) prior to the meeting. Members may meet at the restaurant or inside the Constitution Ave. entrance of the NMNH at 5:00 and walk to the restaurant as a group. Parking is available in the west side parking lot of the NMNH.