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Moving lithospheric modeling forward: Attributes of a
community computer code
GSA TODAY | JUNE 2015 C.M. Cooper, Washington State University, School of the into numerical models that are reliable, portable, and computa-
Environment, P.O. Box 624812, Pullman, Washington 99164-2812, tionally efficient.
USA; Eric Mittelstaedt, University of Idaho, Dept. of Geological
Sciences, 875 Perimeter Drive, MS 3022, Moscow, Idaho 83844- Lithospheric modelers are confronted with a broad range of
3022, USA; Claire A. Currie, University of Alberta, Dept. of Physics, challenges to address these drivers. Scientifically, crucial geolog-
Edmonton, Alberta, Canada T6G 2E1; Jolante van Wijk, New ical processes lack theoretical or empirical descriptions (e.g., vari-
Mexico Institute of Mining and Technology, Dept. of Earth & able fault dip at depth, spacing in shear bands, localization of
Environmental Science, 801 Leroy Place, Socorro, New Mexico deformation, and coupled deformation with melting and melt
87801, USA; Louise K. Kellogg, Lorraine Hwang, University of migration). Incorporating the vast quantity of new data available
California Davis, Earth and Planetary Sciences, Computational through such initiatives as the National Science Foundation’s
Infrastructure for Geodynamics, 2215 Earth and Physical Sciences, EarthScope and data compilations such as Gplates (Qin et al.,
One Shields Avenue, Davis, California 95616, USA; and Ramon 2012) and PetDB (Lehnert et al., 2000) requires both the develop-
Arrowsmith, Arizona State University, School of Earth & Space ment of new data-handling methods and an understanding of
Exploration, P.O. Box 876004, Tempe, Arizona 85287-6004, USA their interrelationships. Added to these challenges are the difficul-
ties in implementing the numerical methods required to run the
We live on a planet with an active surface that is modified and desired simulations, including modeling systems with large-
deformed at multiple temporal and spatial scales owing to diverse magnitude variations in material properties occurring over short
processes occurring at plate boundaries and plate interiors. The spatial scales; maintaining discrete material boundaries as the
processes of mid-ocean-ridge spreading, mountain building, model evolves; and incorporating realistic fault evolution and
subduction of tectonic plates, mantle drag, intra-continental faulting behavior. Lastly, extending models to three dimensions
deformation, earthquakes, and volcanism cross traditional disci- increases the numerical and model complexity, an area that has
plinary boundaries (Fig. 1A). Understanding these lithospheric seen limited development.
processes is valuable not only for intellectual curiosity and to
refine our working knowledge of plate tectonics, but also for Modeling complex systems requires validation and verification
understanding threats to life, property, and infrastructure. of software. Establishing and running benchmarks and test suites
Computer modeling and simulation are increasingly powerful not only “proves” a code, it also provides important insight to the
tools that researchers employ to better understand lithospheric researcher. Limits in parameter space and trade-offs between
deformation and unravel the complex feedbacks that drive the different model specifications become better known.
evolution of Earth’s surface. The field is poised for a significant Benchmarking performance helps to inform the use of computa-
advance to take advantage of recent expansions in computing tional resources and to understand numerical uncertainty.
power, improved representation of idealized processes, increased
data availability, and better communication between software The heterogeneity of the lithosphere translates to a heteroge-
developers and geoscientists. neous approach to modeling lithospheric processes. Computational
approaches employed to address the key scientific interests of the
To move forward as a community, we must address key scien- community tend to be based either in continuum, analytical, or
tific drivers motivating present and future lithospheric deforma- discontinuous methods (Fig. 1B). Usage of these different math-
tion research. The scientific processes to incorporate include ematical methods, several of which may be deployed in any one
melting and melt transport, strain localization and de-localiza- code, depends on the maturity of the research area and the
tion, surface processes (e.g., erosion and deposition), and mantle- specifics of the research question. Individual researchers will
lithosphere interaction. Understanding these requires the often develop numerical techniques and modeling software
integration of results from seismic imaging, the earthquake cycle, capable of solving specific geologic problems. While these efforts
plate boundary evolution, and more realistic Earth-like rheologies often result in numerical codes that are powerful and apt for the
problem at hand, they often do not translate into a more universal
modeling tool.
GSA Today, v. 25, no. 5, doi: 10.1130/GSATG230GW.1.
E-mails: Cooper: cmcooper@wsu.edu; Mittelstaedt: emittelstaedt@uidaho.edu; Currie: claire.currie@ualberta.ca; van Wijk: jvanwijk@ees.nmt.edu; Kellogg: kellogg@
ucdavis.edu; Hwang: lorraine@geodynamics.org; Arrowsmith: ramon.arrowsmith@asu.edu.
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