David L George
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: 37
Debris flow runup on vertical barriers and adverse slopes 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...
Authors
Richard M. Iverson, David L. George, Matthew Logan
Modelling landslide liquefaction, mobility bifurcation and the dynamics of the 2014 Oso disaster 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...
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) 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...
Authors
Richard M. Iverson, David L. George
Clawpack: Building an open source ecosystem for solving hyperbolic PDEs 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...
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 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...
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 H. Schulz, J. Brent Bower
A depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. Physical basis 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...
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. 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
Authors
David L. George, Richard M. Iverson
A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure
Pore-fluid pressure plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. Pore-pressure feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further...
Authors
David L. George, Richard M. Iverson
The GeoClaw software for depth-averaged flows with adaptive refinement The GeoClaw software for depth-averaged flows with adaptive refinement
Many geophysical flow or wave propagation problems can be modeled with two-dimensional depth-averaged equations, of which the shallow water equations are the simplest example. We describe the GeoClaw software that has been designed to solve problems of this nature, consisting of open source Fortran programs together with Python tools for the user interface and flow visualization. This...
Authors
M.J. Berger, D.L. George, R.J. LeVeque, Kyle T. Mandli
Adaptive finite volume methods with well-balanced Riemann solvers for modeling floods in rugged terrain: Application to the Malpasset dam-break flood (France, 1959) Adaptive finite volume methods with well-balanced Riemann solvers for modeling floods in rugged terrain: Application to the Malpasset dam-break flood (France, 1959)
The simulation of advancing flood waves over rugged topography, by solving the shallow-water equations with well-balanced high-resolution finite volume methods and block-structured dynamic adaptive mesh refinement (AMR), is described and validated in this paper. The efficiency of block-structured AMR makes large-scale problems tractable, and allows the use of accurate and stable methods...
Authors
D.L. George
Tsunami modelling with adaptively refined finite volume methods Tsunami modelling with adaptively refined finite volume methods
Numerical modelling of transoceanic tsunami propagation, together with the detailed modelling of inundation of small-scale coastal regions, poses a number of algorithmic challenges. The depth-averaged shallow water equations can be used to reduce this to a time-dependent problem in two space dimensions, but even so it is crucial to use adaptive mesh refinement in order to efficiently...
Authors
R.J. LeVeque, D.L. George, M.J. Berger
Parallelization of GeoClaw code for modeling geophysical flows with adaptive mesh refinement on many-core systems Parallelization of GeoClaw code for modeling geophysical flows with adaptive mesh refinement on many-core systems
We parallelized the GeoClaw code on one-level grid using OpenMP in March, 2011 to meet the urgent need of simulating tsunami waves at near-shore from Tohoku 2011 and achieved over 75% of the potential speed-up on an eight core Dell Precision T7500 workstation [1]. After submitting that work to SC11 the International Conference for High Performance Computing, we obtained an unreleased...
Authors
S. Zhang, D.A. Yuen, A. Zhu, S. Song, David L. George
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.
Science and Products
Filter Total Items: 37
Debris flow runup on vertical barriers and adverse slopes 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...
Authors
Richard M. Iverson, David L. George, Matthew Logan
Modelling landslide liquefaction, mobility bifurcation and the dynamics of the 2014 Oso disaster 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...
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) 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...
Authors
Richard M. Iverson, David L. George
Clawpack: Building an open source ecosystem for solving hyperbolic PDEs 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...
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 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...
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 H. Schulz, J. Brent Bower
A depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. Physical basis 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...
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. 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
Authors
David L. George, Richard M. Iverson
A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure
Pore-fluid pressure plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. Pore-pressure feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further...
Authors
David L. George, Richard M. Iverson
The GeoClaw software for depth-averaged flows with adaptive refinement The GeoClaw software for depth-averaged flows with adaptive refinement
Many geophysical flow or wave propagation problems can be modeled with two-dimensional depth-averaged equations, of which the shallow water equations are the simplest example. We describe the GeoClaw software that has been designed to solve problems of this nature, consisting of open source Fortran programs together with Python tools for the user interface and flow visualization. This...
Authors
M.J. Berger, D.L. George, R.J. LeVeque, Kyle T. Mandli
Adaptive finite volume methods with well-balanced Riemann solvers for modeling floods in rugged terrain: Application to the Malpasset dam-break flood (France, 1959) Adaptive finite volume methods with well-balanced Riemann solvers for modeling floods in rugged terrain: Application to the Malpasset dam-break flood (France, 1959)
The simulation of advancing flood waves over rugged topography, by solving the shallow-water equations with well-balanced high-resolution finite volume methods and block-structured dynamic adaptive mesh refinement (AMR), is described and validated in this paper. The efficiency of block-structured AMR makes large-scale problems tractable, and allows the use of accurate and stable methods...
Authors
D.L. George
Tsunami modelling with adaptively refined finite volume methods Tsunami modelling with adaptively refined finite volume methods
Numerical modelling of transoceanic tsunami propagation, together with the detailed modelling of inundation of small-scale coastal regions, poses a number of algorithmic challenges. The depth-averaged shallow water equations can be used to reduce this to a time-dependent problem in two space dimensions, but even so it is crucial to use adaptive mesh refinement in order to efficiently...
Authors
R.J. LeVeque, D.L. George, M.J. Berger
Parallelization of GeoClaw code for modeling geophysical flows with adaptive mesh refinement on many-core systems Parallelization of GeoClaw code for modeling geophysical flows with adaptive mesh refinement on many-core systems
We parallelized the GeoClaw code on one-level grid using OpenMP in March, 2011 to meet the urgent need of simulating tsunami waves at near-shore from Tohoku 2011 and achieved over 75% of the potential speed-up on an eight core Dell Precision T7500 workstation [1]. After submitting that work to SC11 the International Conference for High Performance Computing, we obtained an unreleased...
Authors
S. Zhang, D.A. Yuen, A. Zhu, S. Song, David L. George
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.