David L George, Ph.D.
I develop mathematical models, numerical methods, and open-source software for simulating geophysical flows. My mathematical focus is PDEs and adaptive finite volume methods, with an application focus on earth-surface flows (e.g., landslides, debris flows, tsunamis, overland flooding).
Current Position:
Research Mathematician, USGS, Cascades Volcano Observatory, 2012-present
Previous Positions:
Mendenhall Postdoctoral Fellow, USGS, Cascades Volcano Observatory, 2008-2012
Postdoctoral Fellow, Department of Applied Mathematics, University of Washington, 2007-2008
Postdoctoral Fellow, Department of Mathematics, University of Utah, 2006-2007.
Education:
Ph.D., Applied Mathematics, University of Washington, Seattle 2006.
M.S., Applied Mathematics, University of Washington, Seattle 2004.
B.S. , B.S. & B.A., Physics, Biology, Anthropology, University of California at Santa Barbara, 1997.
Science and Products
Filter Total Items: 29
Seamless numerical simulation of a hazard cascade in which a landslide triggers a dam-breach flood and consequent debris flow
Numerical simulations of hazard cascades downstream from moraine-dammed lakes commonly must specify linkages between models of discrete processes such as wave overtopping, dam breaching, erosion, and downstream floods or debris flows. Such linkages can be rather arbitrary and can detract from the ability to accurately conserve mass and momentum during complex sequences of events. Here we describ
Authors
David L. George, Richard M. Iverson, Charles M. Cannon
Valid debris-flow models must avoid hot starts
Debris-flow experiments and models commonly use “hot-start” initial conditions in which downslope motion begins when a large force imbalance is abruptly imposed. By contrast, initiation of natural debris flows almost invariably results from small perturbations of static force balances that apply to debris masses poised in steep channels or on steep slopes. Models that neglect these static balanc
Authors
Richard M. Iverson, David L. George
Basal stress equations for granular debris masses on smooth or discretized slopes
Knowledge of basal stresses is essential for analyzing slope stability and modeling the dynamics and erosive potential of debris flows and avalanches. Here we derive and test new algebraic formulas for calculating the shear stress τ and normal stress σ at the base of variable‐thickness granular debris masses in states of static or dynamic equilibrium on slopes. The formulas include a lateral press
Authors
Richard M. Iverson, David L. George
Combining InSAR and GPS to determine transient movement and thickness of a seasonally active low-gradient translational landslide
The combined application of continuous Global Positioning System data (high temporal resolution) with spaceborne interferometric synthetic aperture radar data (high spatial resolution) can reveal much more about the complexity of large landslide movement than is possible with geodetic measurements tied to only a few specific measurement sites. This approach is applied to an ~4 km2 reactivated tran
Authors
Xie Hu, Zhong Lu, Thomas C. Pierson, Rebecca Kramer, David L. George
New methodology for computing tsunami generation by subaerial landslides: Application to the 2015 Tyndall Glacier landslide, Alaska
Landslide-generated tsunamis pose significant hazards and involve complex, multiphase physics that are challenging to model. We present a new methodology in which our depth-averaged two-phase model D-Claw is used to seamlessly simulate all stages of landslide dynamics as well as tsunami generation, propagation, and inundation. Because the model describes the evolution of solid and fluid volume fra
Authors
David L. George, Richard M. Iverson, Charles M. Cannon
Modelling landslide liquefaction, mobility bifurcation and the dynamics of the 2014 Oso disaster
Some landslides move slowly or intermittently downslope, but others liquefy during the early stages of motion, leading to runaway acceleration and high-speed runout across low-relief terrain. Mechanisms responsible for this disparate behaviour are represented in a two-phase, depth-integrated, landslide dynamics model that melds principles from soil mechanics, granular mechanics and fluid mechanics
Authors
Richard M. Iverson, David L. George
Discussion of “The relation between dilatancy, effective stress and dispersive pressure in granular avalanches” by P. Bartelt and O. Buser (DOI: 10.1007/s11440-016-0463-7)
A paper recently published by Bartelt and Buser (hereafter identified as “the authors”) aims to clarify relationships between granular dilatancy and dispersive pressure and to question the effective stress principle and its application to shallow granular avalanches (Bartelt and Buser in Act Geotech 11:549–557, 2). The paper also criticizes our own recent work, which utilizes the concepts of evolv
Authors
Richard M. Iverson, David L. George
Debris flow runup on vertical barriers and adverse slopes
Runup of debris flows against obstacles in their paths is a complex process that involves profound flow deceleration and redirection. We investigate the dynamics and predictability of runup by comparing results from large-scale laboratory experiments, four simple analytical models, and a depth-integrated numerical model (D-Claw). The experiments and numerical simulations reveal the important influ
Authors
Richard M. Iverson, David L. George, Matthew Logan
Clawpack: Building an open source ecosystem for solving hyperbolic PDEs
Clawpack is a software package designed to solve nonlinear hyperbolic partial differential equations using high-resolution finite volume methods based on Riemann solvers and limiters. The package includes a number of variants aimed at different applications and user communities. Clawpack has been actively developed as an open source project for over 20 years. The latest major release, Clawpack 5,
Authors
Richard M. Iverson, K.T. Mandli, Aron J. Ahmadia, M.J. Berger, Donna Calhoun, David L. George, Y. Hadjimichael, David I. Ketcheson, Grady L. Lemoine, Randall J. LeVeque
Landslide mobility and hazards: implications of the 2014 Oso disaster
Landslides reflect landscape instability that evolves over meteorological and geological timescales, and they also pose threats to people, property, and the environment. The severity of these threats depends largely on landslide speed and travel distance, which are collectively described as landslide “mobility”. To investigate causes and effects of mobility, we focus on a disastrous landslide that
Authors
Richard M. Iverson, David L. George, Kate E. Allstadt, Mark E. Reid, Brian D. Collins, James W. Vallance, Steve P. Schilling, Jonathan W. Godt, Charles Cannon, Christopher S. Magirl, Rex L. Baum, Jeffrey A. Coe, William Schulz, J. Brent Bower
A depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. Physical basis
To simulate debris-flow behaviour from initiation to deposition, we derive a depth-averaged, two-phase model that combines concepts of critical-state soil mechanics, grain-flow mechanics and fluid mechanics. The model's balance equations describe coupled evolution of the solid volume fraction, m, basal pore-fluid pressure, flow thickness and two components of flow velocity. Basal friction is evalu
Authors
Richard M. Iverson, David L. George
A depth-averaged debris-flow model that includes the effects of evolving dilatancy: II. Numerical predictions and experimental tests.
We evaluate a new depth-averaged mathematical model that is designed to simulate all stages of debris-flow motion, from initiation to deposition. A companion paper shows how the model’s five governing equations describe simultaneous evolution of flow thickness, solid volume fraction, basal pore-fluid pressure, and two components of flow momentum. Each equation contains a source term that represent
Authors
David L. George, Richard M. Iverson
Non-USGS Publications**
D. L. George, 2008: Augmented Riemann solvers for the shallow water equations over variable topography with steady states and inundation. J. Comput. Phys., 227(6): 3089--3113.
R. J. LeVeque and D. L. George, 2008: High-resolution finite volume methods for the shallow water equations with topography and dry-states. In P. L. Liu, C. Synolakis, and H. Yeh, editors, Advanced Numerical Models for Simulating Tsunami Waves and Runup, vol. 10 of Advances in Coastal and Ocean Engineering, pp. 43--73. World Scientific.
D. L. George and R. J. LeVeque, 2008: High-resolution methods and adaptive refinement for tsunami propagation and inundation. In S. Benzoni-Gavage and D. Serre, editors, Hyperbolic Problems: Theory, Numerics, Applications, pp. 541--549, Springer.
D. L. George and R. J. LeVeque, 2006: Finite volume methods and adaptive refinement for global tsunami propagation and inundation. Science of Tsunami Hazards, Vol. 24. No. 5, 319--328.
**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.
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Filter Total Items: 29
Seamless numerical simulation of a hazard cascade in which a landslide triggers a dam-breach flood and consequent debris flow
Numerical simulations of hazard cascades downstream from moraine-dammed lakes commonly must specify linkages between models of discrete processes such as wave overtopping, dam breaching, erosion, and downstream floods or debris flows. Such linkages can be rather arbitrary and can detract from the ability to accurately conserve mass and momentum during complex sequences of events. Here we describAuthorsDavid L. George, Richard M. Iverson, Charles M. CannonValid debris-flow models must avoid hot starts
Debris-flow experiments and models commonly use “hot-start” initial conditions in which downslope motion begins when a large force imbalance is abruptly imposed. By contrast, initiation of natural debris flows almost invariably results from small perturbations of static force balances that apply to debris masses poised in steep channels or on steep slopes. Models that neglect these static balancAuthorsRichard M. Iverson, David L. GeorgeBasal stress equations for granular debris masses on smooth or discretized slopes
Knowledge of basal stresses is essential for analyzing slope stability and modeling the dynamics and erosive potential of debris flows and avalanches. Here we derive and test new algebraic formulas for calculating the shear stress τ and normal stress σ at the base of variable‐thickness granular debris masses in states of static or dynamic equilibrium on slopes. The formulas include a lateral pressAuthorsRichard M. Iverson, David L. GeorgeCombining InSAR and GPS to determine transient movement and thickness of a seasonally active low-gradient translational landslide
The combined application of continuous Global Positioning System data (high temporal resolution) with spaceborne interferometric synthetic aperture radar data (high spatial resolution) can reveal much more about the complexity of large landslide movement than is possible with geodetic measurements tied to only a few specific measurement sites. This approach is applied to an ~4 km2 reactivated tranAuthorsXie Hu, Zhong Lu, Thomas C. Pierson, Rebecca Kramer, David L. GeorgeNew methodology for computing tsunami generation by subaerial landslides: Application to the 2015 Tyndall Glacier landslide, Alaska
Landslide-generated tsunamis pose significant hazards and involve complex, multiphase physics that are challenging to model. We present a new methodology in which our depth-averaged two-phase model D-Claw is used to seamlessly simulate all stages of landslide dynamics as well as tsunami generation, propagation, and inundation. Because the model describes the evolution of solid and fluid volume fraAuthorsDavid L. George, Richard M. Iverson, Charles M. CannonModelling landslide liquefaction, mobility bifurcation and the dynamics of the 2014 Oso disaster
Some landslides move slowly or intermittently downslope, but others liquefy during the early stages of motion, leading to runaway acceleration and high-speed runout across low-relief terrain. Mechanisms responsible for this disparate behaviour are represented in a two-phase, depth-integrated, landslide dynamics model that melds principles from soil mechanics, granular mechanics and fluid mechanicsAuthorsRichard M. Iverson, David L. GeorgeDiscussion of “The relation between dilatancy, effective stress and dispersive pressure in granular avalanches” by P. Bartelt and O. Buser (DOI: 10.1007/s11440-016-0463-7)
A paper recently published by Bartelt and Buser (hereafter identified as “the authors”) aims to clarify relationships between granular dilatancy and dispersive pressure and to question the effective stress principle and its application to shallow granular avalanches (Bartelt and Buser in Act Geotech 11:549–557, 2). The paper also criticizes our own recent work, which utilizes the concepts of evolvAuthorsRichard M. Iverson, David L. GeorgeDebris flow runup on vertical barriers and adverse slopes
Runup of debris flows against obstacles in their paths is a complex process that involves profound flow deceleration and redirection. We investigate the dynamics and predictability of runup by comparing results from large-scale laboratory experiments, four simple analytical models, and a depth-integrated numerical model (D-Claw). The experiments and numerical simulations reveal the important influAuthorsRichard M. Iverson, David L. George, Matthew LoganClawpack: Building an open source ecosystem for solving hyperbolic PDEs
Clawpack is a software package designed to solve nonlinear hyperbolic partial differential equations using high-resolution finite volume methods based on Riemann solvers and limiters. The package includes a number of variants aimed at different applications and user communities. Clawpack has been actively developed as an open source project for over 20 years. The latest major release, Clawpack 5,AuthorsRichard M. Iverson, K.T. Mandli, Aron J. Ahmadia, M.J. Berger, Donna Calhoun, David L. George, Y. Hadjimichael, David I. Ketcheson, Grady L. Lemoine, Randall J. LeVequeLandslide mobility and hazards: implications of the 2014 Oso disaster
Landslides reflect landscape instability that evolves over meteorological and geological timescales, and they also pose threats to people, property, and the environment. The severity of these threats depends largely on landslide speed and travel distance, which are collectively described as landslide “mobility”. To investigate causes and effects of mobility, we focus on a disastrous landslide thatAuthorsRichard M. Iverson, David L. George, Kate E. Allstadt, Mark E. Reid, Brian D. Collins, James W. Vallance, Steve P. Schilling, Jonathan W. Godt, Charles Cannon, Christopher S. Magirl, Rex L. Baum, Jeffrey A. Coe, William Schulz, J. Brent BowerA depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. Physical basis
To simulate debris-flow behaviour from initiation to deposition, we derive a depth-averaged, two-phase model that combines concepts of critical-state soil mechanics, grain-flow mechanics and fluid mechanics. The model's balance equations describe coupled evolution of the solid volume fraction, m, basal pore-fluid pressure, flow thickness and two components of flow velocity. Basal friction is evaluAuthorsRichard M. Iverson, David L. GeorgeA depth-averaged debris-flow model that includes the effects of evolving dilatancy: II. Numerical predictions and experimental tests.
We evaluate a new depth-averaged mathematical model that is designed to simulate all stages of debris-flow motion, from initiation to deposition. A companion paper shows how the model’s five governing equations describe simultaneous evolution of flow thickness, solid volume fraction, basal pore-fluid pressure, and two components of flow momentum. Each equation contains a source term that representAuthorsDavid L. George, Richard M. IversonNon-USGS Publications**
D. L. George, 2008: Augmented Riemann solvers for the shallow water equations over variable topography with steady states and inundation. J. Comput. Phys., 227(6): 3089--3113.R. J. LeVeque and D. L. George, 2008: High-resolution finite volume methods for the shallow water equations with topography and dry-states. In P. L. Liu, C. Synolakis, and H. Yeh, editors, Advanced Numerical Models for Simulating Tsunami Waves and Runup, vol. 10 of Advances in Coastal and Ocean Engineering, pp. 43--73. World Scientific.D. L. George and R. J. LeVeque, 2008: High-resolution methods and adaptive refinement for tsunami propagation and inundation. In S. Benzoni-Gavage and D. Serre, editors, Hyperbolic Problems: Theory, Numerics, Applications, pp. 541--549, Springer.D. L. George and R. J. LeVeque, 2006: Finite volume methods and adaptive refinement for global tsunami propagation and inundation. Science of Tsunami Hazards, Vol. 24. No. 5, 319--328.**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.
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