Tamara Jeppson is a Mendenhall Postdoc in the Earthquake Science Center.
Science and Products
Geothermal slide-hold-slide experiments on bare surface Westerly granite
Laboratory slide-hold-slide tests, combined with flow through tests, conducted on Westerly granite with 30 degree sawcut. Tests were conducted with a constant confining pressure of 30 MPa with an average pore pressure of 10 MPa at temperatures of 23 and 200 degC. Three fluid flow conditions were examined (1) no flow, (2) cycled flow, and (3) continuous flow.
Strength recovery in quartzite is controlled by changes in friction in experiments at hydrothermal conditions up to 200°C
The rate of fault zone restrengthening between earthquakes can be influenced by both frictional and cohesive healing processes. Friction is dependent on effective normal stress while cohesion is independent of normal stress, potentially explaining—in part—the lack of depth dependence of earthquake stress drops. Although amenable to laboratory testing, few studies have systematically addressed the
Authors
Tamara Nicole Jeppson, David A. Lockner, Nicholas M. Beeler, Stephen H. Hickman
Effect of thermal and mechanical processes on hydraulic transmissivity evolution
Fracture healing is a critical component of enhanced geothermal systems, the earthquake cycle, and induced seismicity. Accordingly, there is significant interest in understanding the process of healing and its effects on fluid transport. The creation, reactivation, and sustainability of fracture networks depend on complex coupling among thermal, hydraulic, mechanical, and chemical processes. We us
Authors
Tamara Nicole Jeppson, David A. Lockner, Joshua M. Taron, Diane E. Moore, Brian D. Kilgore, Nicholas M. Beeler, Stephen H. Hickman
Impact of fluid-rock interaction on strength and hydraulic transmissivity rvolution in shear fractures under hydrothermal conditions
Reactivated shear fractures contribute to the creation of pervasive fracture networks in geothermal systems. The creation, reactivation, and sustainability of fracture networks depend on complex coupling among thermal, hydraulic, mechanical, and chemical (THMC) processes. However, most laboratory experiments focus either solely on how fluid transport properties evolve in stationary fractures at el
Authors
Tamara Nicole Jeppson, David A. Lockner
Velocity-porosity relations in carbonate and siliciclastic subduction zone input materials
The mechanical, physical, and frictional properties of incoming materials play an important role in subduction zone structure and slip behavior because these properties influence the strength of the accretionary wedge and megathrust plate boundary faults. Incoming sediment sections often show an increase in compressional wave speed (Vp) and a decrease in porosity with depth due to consolidation. T
Authors
Tamara Nicole Jeppson, Hiroko Kitajima
Strength recovery and sealing under hydrothermal conditions
While there is significant evidence for healing in natural faults, geothermal reservoirs, and lab experiments, the thermal, hydraulic, mechanical, and chemical interactions that influence healing are poorly understood. We present preliminary results of triaxial slide-hold-slide experiments to constrain rates and mechanisms of healing. Experiments were conducted on gouge composed of Westerly granit
Authors
Tamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. Taron
Evolution of fluid transmissivity and strength recovery of shear fractures under hydrothermal conditions
Geothermal systems rely on the presence of long-lived and high-volume, permeable fracture systems. The creation, reactivation, and sustainability of these systems depend on complex coupling among thermal, hydraulic, mechanical, and chemical (THMC) processes occurring in geothermal reservoirs. In part due to a paucity of experimental data, the evolution of fractures at geothermal conditions in resp
Authors
Tamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. Taron
Bedrock geology of DFDP-2B, central Alpine Fault, New Zealand
During the second phase of the Alpine Fault, Deep Fault Drilling Project (DFDP) in the Whataroa River, South Westland, New Zealand, bedrock was encountered in the DFDP-2B borehole from 238.5–893.2 m Measured Depth (MD). Continuous sampling and meso- to microscale characterisation of whole rock cuttings established that, in sequence, the borehole sampled amphibolite facies, Torlesse Composite Terra
Authors
Virginia G. Toy, Rupert Southerland, John Townend, Michael J. Allen, Leeza Becroft, Austin Boles, Carolyn Boulton, Brett Carpenter, Alan K. Cooper, Simon C. Cox, Christopher Daube, Daniel R. Faulkner, Angela Halfpenny, Naoki Kato, Stephen Keys, Martina Kirilova, Yusuke Kometani, Timothy Little, Elisabetta Mariani, Benjamin Melosh, Catriona D. Menzies, Luiz Morales, Chance Morgan, Hiroshi Mori, Andre Niemeijer, Richard Norris, David Prior, Katrina Sauer, Anja Schleicher, Norio Shigematsu, Damon A.H. Teagle, Harold Tobin, Robert Valdez, Jack Williams, Samantha Yeo, Laura-May Baratin, Nicolas C. Barth, Adrian Benson, Caroline Boese, Bernard Celerier, Calum J. Chamberlain, Ronald Conze, Jamie Coussens, Lisa Craw, Mai-Linh Doan, Jennifer L. Eccles, Jason Grieve, Julia Grochowski, Anton Gulley, Jamie Howarth, Katrina D. Zamudio, Lucie Janku-Capova, Tamara Nicole Jeppson, Robert M. Langridge, Deirdre Mallyon, Ray Marx, Cecile Massiot, Loren Mathewson, Josephine Moore, Osamu Nishikawa, Brent Pooley, Alex Pyne, Martha K. Savage, Doug Schmitt, Sam Taylor-Offord, Phaedra Upton, Konrad C. Weaver, Thomas Wiersberg, Martin Zimmer
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Data
Geothermal slide-hold-slide experiments on bare surface Westerly granite
Laboratory slide-hold-slide tests, combined with flow through tests, conducted on Westerly granite with 30 degree sawcut. Tests were conducted with a constant confining pressure of 30 MPa with an average pore pressure of 10 MPa at temperatures of 23 and 200 degC. Three fluid flow conditions were examined (1) no flow, (2) cycled flow, and (3) continuous flow. - Publications
Strength recovery in quartzite is controlled by changes in friction in experiments at hydrothermal conditions up to 200°C
The rate of fault zone restrengthening between earthquakes can be influenced by both frictional and cohesive healing processes. Friction is dependent on effective normal stress while cohesion is independent of normal stress, potentially explaining—in part—the lack of depth dependence of earthquake stress drops. Although amenable to laboratory testing, few studies have systematically addressed theAuthorsTamara Nicole Jeppson, David A. Lockner, Nicholas M. Beeler, Stephen H. HickmanEffect of thermal and mechanical processes on hydraulic transmissivity evolution
Fracture healing is a critical component of enhanced geothermal systems, the earthquake cycle, and induced seismicity. Accordingly, there is significant interest in understanding the process of healing and its effects on fluid transport. The creation, reactivation, and sustainability of fracture networks depend on complex coupling among thermal, hydraulic, mechanical, and chemical processes. We usAuthorsTamara Nicole Jeppson, David A. Lockner, Joshua M. Taron, Diane E. Moore, Brian D. Kilgore, Nicholas M. Beeler, Stephen H. HickmanImpact of fluid-rock interaction on strength and hydraulic transmissivity rvolution in shear fractures under hydrothermal conditions
Reactivated shear fractures contribute to the creation of pervasive fracture networks in geothermal systems. The creation, reactivation, and sustainability of fracture networks depend on complex coupling among thermal, hydraulic, mechanical, and chemical (THMC) processes. However, most laboratory experiments focus either solely on how fluid transport properties evolve in stationary fractures at elAuthorsTamara Nicole Jeppson, David A. LocknerVelocity-porosity relations in carbonate and siliciclastic subduction zone input materials
The mechanical, physical, and frictional properties of incoming materials play an important role in subduction zone structure and slip behavior because these properties influence the strength of the accretionary wedge and megathrust plate boundary faults. Incoming sediment sections often show an increase in compressional wave speed (Vp) and a decrease in porosity with depth due to consolidation. TAuthorsTamara Nicole Jeppson, Hiroko KitajimaStrength recovery and sealing under hydrothermal conditions
While there is significant evidence for healing in natural faults, geothermal reservoirs, and lab experiments, the thermal, hydraulic, mechanical, and chemical interactions that influence healing are poorly understood. We present preliminary results of triaxial slide-hold-slide experiments to constrain rates and mechanisms of healing. Experiments were conducted on gouge composed of Westerly granitAuthorsTamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. TaronEvolution of fluid transmissivity and strength recovery of shear fractures under hydrothermal conditions
Geothermal systems rely on the presence of long-lived and high-volume, permeable fracture systems. The creation, reactivation, and sustainability of these systems depend on complex coupling among thermal, hydraulic, mechanical, and chemical (THMC) processes occurring in geothermal reservoirs. In part due to a paucity of experimental data, the evolution of fractures at geothermal conditions in respAuthorsTamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. TaronBedrock geology of DFDP-2B, central Alpine Fault, New Zealand
During the second phase of the Alpine Fault, Deep Fault Drilling Project (DFDP) in the Whataroa River, South Westland, New Zealand, bedrock was encountered in the DFDP-2B borehole from 238.5–893.2 m Measured Depth (MD). Continuous sampling and meso- to microscale characterisation of whole rock cuttings established that, in sequence, the borehole sampled amphibolite facies, Torlesse Composite TerraAuthorsVirginia G. Toy, Rupert Southerland, John Townend, Michael J. Allen, Leeza Becroft, Austin Boles, Carolyn Boulton, Brett Carpenter, Alan K. Cooper, Simon C. Cox, Christopher Daube, Daniel R. Faulkner, Angela Halfpenny, Naoki Kato, Stephen Keys, Martina Kirilova, Yusuke Kometani, Timothy Little, Elisabetta Mariani, Benjamin Melosh, Catriona D. Menzies, Luiz Morales, Chance Morgan, Hiroshi Mori, Andre Niemeijer, Richard Norris, David Prior, Katrina Sauer, Anja Schleicher, Norio Shigematsu, Damon A.H. Teagle, Harold Tobin, Robert Valdez, Jack Williams, Samantha Yeo, Laura-May Baratin, Nicolas C. Barth, Adrian Benson, Caroline Boese, Bernard Celerier, Calum J. Chamberlain, Ronald Conze, Jamie Coussens, Lisa Craw, Mai-Linh Doan, Jennifer L. Eccles, Jason Grieve, Julia Grochowski, Anton Gulley, Jamie Howarth, Katrina D. Zamudio, Lucie Janku-Capova, Tamara Nicole Jeppson, Robert M. Langridge, Deirdre Mallyon, Ray Marx, Cecile Massiot, Loren Mathewson, Josephine Moore, Osamu Nishikawa, Brent Pooley, Alex Pyne, Martha K. Savage, Doug Schmitt, Sam Taylor-Offord, Phaedra Upton, Konrad C. Weaver, Thomas Wiersberg, Martin ZimmerNon-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.