Each year, the Daniel S. Tudor Commemorative Lecture Series brings a geophysicist of international reputation to share geophysical knowledge with faculty and students at Indiana University. The lecture series recognizes the accomplishments of one of Indiana University’s most distinguished alumni, Daniel S. Tudor. Dan was among the most loyal, supportive, and generous of our alumni. He was named President fo Exploration Services for Chevron Geosciences in 1984, and he retired as President of Chevron Exploration and Production Services in 1993.
Daniel Tudor Lecture
Previous Tudor Lectures
2019 - Kyle Anderson, USGS
2017 - Paul Segall, Stanford University
2016 - John Shaw, Harvard University
2014 - Bill Ellsworth, USGS Menlo Park, CA
2013 - Terry Engelder, Penn State University
2012 - Marcia McNutt, U.S. Geological Survey
2010 - Michael Bostock, University of British Columbia
2009 - Henry W. Posamentier, Chevron Energy Technology Co.
2007 - G. Randy Keller, University of Oklahoma
2006 - Walter D. Mooney, U.S. Geological Survey
2005 - N. Ross Hill, Chevron Energy Technology Co.
2004 - Fred J. Hilterman, University of Houston
2001 - John W. Gibson Jr., Landmark Graphics Corp.
2000 - Thomas J. Schull, Chevron USA Production Co.
February 20 2017
Speaker: Paul Segall, Stanford University.
Title: Beyond Rangely: Understanding the Mechanics of Induced Seismicity
Abstract: Since the pioneering study at Rangely, Colorado, induced seismicity due to fluid injection has been understood to result from a decrease in effective normal stress acting on faults due to increase in pore-fluid pressure. Much attention has thus been given to the spatiotemporal distribution of pore-pressure resulting from injection. Yet, there are well documented cases in which oil and gas production, with dramatic decreases in reservoir pressure have triggered earthquakes. This is opposite to expectation based on the effective stress concept, but can be well understood with Biot’s theory of poroelasticity.
I will explore whether poroelastic effects are important in injection induced seismicity. Several surprising results follow from simple models, including that abrupt shut-in (cessation of injection) can lead to locally sharp increases in seismicity rate. In addition, poroelastic stressing can destabilize faults that are hydraulically isolated from injection horizons. Finally, the maximum magnitude of induced events has been observed to occur post-injection, which presents a clear problem for so-called ‘stop light’ mitigation systems. I suggest that under low ambient shear stresses rupture extents are limited by the time varying volume of perturbed crust. This leads to time dependence in the frequency magnitude distribution of earthquake sizes, as has been observed in Basel, Switzerland. In this limit, larger events post shut-in are not unexpected.
About Paul Segall
Paul Segall has been a Professor of Geophysics at Stanford University since 1989. He received a Ph.D. from Stanford in 1981 and an M.S. from Case Western Reserve University in 1976. He worked as a Geologist for the USGS from 1981-1989. He studies active earthquake and volcanic process through data collection, inversion, and theoretical modeling. Using techniques such as the Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) he and his students measure deformation in space and time and invert these data for the geometry of faults and magma chambers, and spatiotemporal variations in fault slip-rate and magma chamber dilation.
He develops and tests models of active plate boundaries such as the San Andreas, and the Cascade subduction zone, the nucleation of earthquakes, slow slip events, and the physics of magma migration leading to volcanic eruptions. He is an AGU and GSA Fellow and has received the prestigious AGU Macelwane (1990) and Whitten (2014) medals. He was elected a member of the National Academy of Sciences in 2016.
April 11, 2016
Speaker: John Shaw, Harvard University.
Title: Deformation in active thrust sheets through multiple earthquake cycles.
Abstract: Active thrust faults pose significant earthquake hazards in the western United States and in many other convergent plate boundaries around the world. Traditional paleoseismic methods for assessing such hazards have relied primarily on fault offsets of stratigraphic horizons and/or geomorphic markers.
However, recent events, such as the 1999 Chi Chi (M 7.6), Taiwan, 2008 Wenchuan (M 7.9), China, and 2015 Gorkha (M 7.8), Nepal earthquakes demonstrate the complex nature of thrust fault ruptures, which often exhibit significant components of coseismic folding, in addition to faulting. Indeed, many active thrust faults – or portions of faults – are blind, such that deformation at the Earth’s surface is characterized exclusively by folding.
We will explore a series of active thrust sheets in California and the Junggar basin, China, that are constrained by fault scarps, folded marine and fluvial terraces, and subsurface geophysical data. These examples highlight how fault slip and seismic moment release at depth are partitioned into components of folding and faulting in the shallow subsurface. This, in turn, provides methods for using surface deformation patterns such as folding to infer fault behavior at depth for improved seismic hazard assessments.
February 6, 2012
Speaker: Dr. Marcia McNutt, Director of USGS.
Title: U.S. Energy Outlook: Whatever Happened to "Peak Oil"?
Brown–bag lecture: Earthquakes Near and Far: A Study in Community Resiliency.
Quoting the Indiana Daily Student: As a kickoff to the 175th birthday of IU’s Geological Survey, U.S. Geological Survey Director Marcia McNutt was invited to campus to give a lecture titled “Earthquakes Near and Far: A Study in Community Resiliency,” which took place Monday afternoon in the IU Fine Arts Auditorium.
The event was organized by the Department of Geological Sciences and IU Geology Professor Michael Hamburger.
“It’s like the political science department bringing the president to speak for them,” Hamburger said. “It really helps to connect geology with the issues of today and helps to explain why geology is important.”
While the audience awaited McNutt’s arrival, a small group of fellow geologists, including IU Assistant Director for Research Todd Thompson and USGS Geologist Kathleen Fowler, pored over a geological map of the bedrock of Monroe County. They traced the fault lines with their fingers and shared their mutual fascination for the subject before the presentation.
March 22, 2010
Speaker: Michael Bostock, University of British Columbia.
Title: Fate of water in the Cascadia Forearc Unveiled by Teleseismic Imaging.
Abstract: The past decade has witnessed the deployment of large numbers of broadband seismometers along the Cascadia forearc. A high density of sampling has permitted the mapping of subduction zone structure along and across strike using scattered teleseismic body waves. Forearc structural signatures across profiles sampling central Oregon, Puget Sound, and Vancouver Island are remarkably similar.
A ~5 km thick, dipping low-velocity zone (LVZ) extending to depths of >50 km is inferred here to represent subducting oceanic crust of the Juan de Fuca plate. Estimates of Poisson’s ratio within the shallow LVZ are extremely high, between 0.35 and 0.4, and cannot be attributed to lithology. Rather, they are interpreted to manifest near-lithostatic, pore-fluid pressures generated through metamorphic dehydration reactions within the oceanic crust.
Accordingly, the plate interface must represent an impermeable boundary at these depths. Farther down dip, the signature of the LVZ fades as its upper, followed by lower, boundaries become seismically indistinguishable from ambient mantle. Thermo-petrological models predict that metabasalt undergo a final transformation to nominally anhydrous eclogite at these depths, consistent with the seismic observation.
Immediately above the LVZ, within the mantle wedge, there is a significant velocity reduction that is sufficient to erase the seismic contrast that typically marks the transition from mantle wedge to continental crust. This feature is inferred to be due to the combined presence of antigorite and free water (at elevated pore pressure)resulting from eclogitization, consistent with thermo-petrological models.
A number of other geophysical (seismic reflection, gravity, magnetics) observations lend support to the serpentinization interpretation and demonstrate its continuity along strike. Both serpentinization and eclogitization involve large (10%-20%) changes in volume that are likely accommodated through fracturing, thereby promoting a dramatic increase in permeability across the plate interface near the mangle wedge corner. This location coincides with hypocentral locations of non-volcanic tremor and, given the oft-inferred association of tremor fluids, we propose that changes in plate interface permeability may play a key role in tremor generation.
Henry W. Posamentier
March 2, 2009
Speaker: Henry W. Posamentier Senior Consultant Geologist Chevron Energy Technology Company.
Title: Using 3d seismic data to predict lithology in the subsurface: applications of seismic geomorphology and seismic stratigraphy from deep water to shelf.
February 19 2007
Speaker: Randy Keller, University of Oklahoma.
Title: Continental Rifts: Integrated Geophysical Studies and Tectonic Implications
February 27, 2006
Speaker: Dr. Walter Mooney, US Geological Survey
Title: The Great Sumatra-Andaman Islands Earthquake and Tsunami: Observations and Regional Preparations for Future Tsunamis
Abstract: The December, 2004, Sumatra-Andaman Islands earthquake and tsunami caused an estimated 280,000 deaths in the Indian Ocean region. This enormous (M = 9.2) earthquake was recorded by modern field instrumentation and has led to profound insights into the origin of great earthquakes and the tsunamis they generate. This talk will summarize the scientific state-of-the-art regarding this devastating earthquake, and will discuss plans to avoid such disasters in the future.
January 21, 2005
Speaker: Ross Hill, Chevron Oil
Title: Seismic Imaging of Complex Geological Structures
October 4, 2001
Speaker: John Gibson, Landmark Corporation
Title: The Future of Petroleum Geophysics - Great Scientist Needed Immediately - Apply Within.