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1A 1B
Figure 1. (A) The study of how the lithosphere deforms spans disciplines to help us understand earth processes on a subatomic to global scale and from
microseconds to hundreds of millions of years. The wide range of scales in space and time are challenging to accommodate using today’s computation resources
(after Hwang et al., 2014). (B) Mathematical techniques commonly used in geophysics research can be classified as continuum, analytical, or discontinuous
methods, posing computational and numerical challenges for multidisciplinary research.
For example, while one technique might be optimal for under-
standing the evolution of ocean basins and localized faulting at a
mid-ocean ridge, it may not be applicable for regional-scale
subduction dynamics. Similarly, techniques used to model stress/
strain fields over the earthquake cycle may not be optimal for
understanding stress/strain fields generated during continental
collision. In addition, while grain-scale processes are critical in
understanding how rocks deform, it may not be necessary to
include these small-scale effects when trying to understand conti-
nental scale deformation. Furthermore, we understand that the
lithosphere behaves as an elasto-visco-plastic material, but many
of the governing characteristics of this rheologic behavior are not
well defined and thus not easy to incorporate into numerical
models. Large-scale geophysical observatories, such as
EarthScope’s real-time seismological and geodetic data streams
(Williams et al., 2010, http://www.earthscope.org/assets/uploads/
pages/es_sci_plan_hi.pdf), coupled with the breadth of research
questions (both basic and applied) focusing on the structure and
evolution of the North American continent provide a great inter-
pretive challenge that requires a broad range of lithospheric
dynamics modeling capabilities.
Therein lies the challenge of modeling lithospheric processes:
Can we build a community code (or suite of codes) that can span the
breadth of lithospheric processes while maintaining the required
numerical rigor to solve such problems and that is offered at a level
that is accessible to users with a wide range of experiences?
The ideas in this article emerged from the 2014 CIG EarthScope
Institute for Lithospheric Modeling workshop (http://geodynamics
.org/cig/events/calendar/2014-cig-earthscope-institute-lithospheric-
modeling-workshop/meeting/), a joint workshop of the
Computational Infrastructure for Geodynamics’ (CIG) long-term
tectonics community and the EarthScope National Office. This was
the first dedicated workshop within North America for the modeling
of lithospheric deformation in more than a decade; the topic has
previously been wrapped into larger workshops and national meet-
ings with a broader scope, diluting many of the discussions pertinent
to lithospheric deformation modeling. The workshop highlighted
the complexity and variety within the discipline, suggesting that a
“one size fits many”—that is, a single community code that fits most
researchers’ needs—might not be the best approach. Rather, a move
toward a common core or engine that researchers can build upon or GSA TODAY | www.geosociety.org/gsatoday
modify to suit their specific research problems might be a more real-
istic and fruitful endeavor. Community-developed scientific codes
can build on established numerical methods (which are ideally
benchmarked, documented, and open-source) while taking advan-
tage of state-of-the-art techniques. As a community of user-devel-
opers is established, a shared expertise emerges that in turn leads to
improved computational tools.
To begin this journey, we must build a community vision. The
workshop articulated the following as needs: to (1) continue the
conversations, either in person at meetings or via online forums;
(2) establish the means to collate best practices and known
successful numerical techniques; (3) develop benchmarks and use
cases—specific examples of scientific or technical problems or
questions, with identified goals, key users, and outcomes; and
(4) collectively begin a community-wide benchmark exercise in
order to assess current computing capabilities and guide the
development of the next generation of models. Through these
efforts, the community as a whole can move lithospheric deforma-
tion modeling into the next frontier. This requires your involvement;
please consider visiting the CIG website (www.geodynamics.org)
and joining the list-serves and online community.
REFERENCES CITED
Hwang, L., Jordan, T., Kellogg, L., Tromp, J., and Willemann, R., 2014,
Advancing Solid Earth System Science through High Performance
Computing: http://geodynamics.org/cig/files/1614/0224/2811/AdvHPC-
June2014.pdf (last accessed 27 Jan. 2015).
Lehnert, K., Su, Y., Langmuir, C., Sarbas, B., and Nohl, U., 2000, A global
geochemical database structure for rocks: Geochemistry Geophysics
Geosystems, v. 1, no. 5, doi: 10.1029/1999GC000026.
Qin, X., Müller, R.D., Cannon, J., Landgrebe, T.C.W., Heine, C., Watson, R.J.,
and Turner, M., 2012, The GPlates Geological Information Model and
Markup Language, in Geoscientific Instrumentation, Methods and Data
Systems Discussion, v. 2, p. 365–428, doi: 10.5194/gid-2-365-2012.
Williams, M.L., Fischer, K.M., Freymueller, J.T., Tikoff, B., Tréhu, A.M., et al.,
2010, Unlocking the Secrets of the North American Continent: An
EarthScope Science Plan for 2010–2020, February, 2010, 78 p., http://
www.earthscope.org/assets/uploads/pages/es_sci_plan_hi.pdf (last accessed
27 Jan. 2015).
Manuscript received 28 Aug. 2014; accepted 2 Dec. 2014.
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