Also known as
Model type Single
Model part of larger framework
Note on status model
Date note status model
Incorporated models or components:
Spatial dimensions 3D
Spatial extent Continental, Landscape-Scale, Regional-Scale
Model domain Terrestrial, Geodynamic
One-line model description An updated Lagrangian explicit finite difference code for modeling a finitely deforming elasto-visco-plastic solid in 3D.
Extended model description SNAC can solve momentum and heat energy balance equations in 3D solid with complicated rheology. Lagrangian description of motion adopted in SNAC makes it easy to monitor surface deformation during a crustal or continental scale tectonic event as well as introduce surface processes into a model.
Name Eunseo Choi
Type of contact Model developer
Institute / Organization Lamont-Doherty Earth Observatory
Postal address 1 P.O. Box 1000
Postal address 2 61 Rt. 9W
Town / City Palisades
Postal code 10964
State New York
Country United States
Email address
Phone 845-365-8813
Fax 845-365-8156

Supported platforms
Linux, Mac OS
Other platform
Programming language


Other program language
Code optimized Single Processor, Multiple Processors
Multiple processors implemented
Nr of distributed processors
Nr of shared processors
Start year development 2003
Does model development still take place? Yes
If above answer is no, provide end year model development
Code development status Active
When did you indicate the 'code development status'? 2020
Model availability As code
Source code availability
(Or provide future intension)
Through web repository
Source web address
Source csdms web address
Program license type GPL v2
Program license type other
Memory requirements tipically < 1 GB
Typical run time hours to days

Describe input parameters In XML format, the following groups of parameters are specified:

simulation control group: total model time, time step, damping, etc. plugins: elasticity, viscoelasticity, temperature solver, etc. domain description group: domain size, element numbers, etc. initial and boundary conditions group

Input format ASCII
Other input format XML
Describe output parameters Nodal field data: velocity, temperature

Element-centered (discontinuous) field data: strain rate, stress, plastic strain, etc.

Output format Binary
Other output format
Pre-processing software needed? No
Describe pre-processing software
Post-processing software needed? Yes
Describe post-processing software A simple C program that converts binary outputs into ascii data file in the VTK format.
Visualization software needed? Yes
If above answer is yes
Other visualization software ParaView or anything that can visualize VTK files.

Describe processes represented by the model Momentum balance in solid continuum under gravity and kinematic boundary conditions.
Describe key physical parameters and equations Newton's second law in the dynamic form is damped to acquire static or quasi-static solutions. Among importance parameters are those for a constitutive model (elastic moduli, linear and non-linear viscosity, and parameters for strain-weakening plasticity) and damping parameters.
Describe length scale and resolution constraints No inherent length scale or resolution as long as the continuum hypothesis is satisfied. A practical constraint on length scale and resolution is computational cost.
Describe time scale and resolution constraints Time scale is essentially set by the Courant condition: practially by P-wave velocity or maxwell time according to the constitutive model being considered. However, the mass scaling technique allows significantly increased time steps values from the usual dynamic one.
Describe any numerical limitations and issues Extreme deformation of mesh is expected during large deformationin the updated Lagrangian formulation but prevented by regridding. The numerical diffusion due to regridding, however, can sometime make structures (e.g. shear localization) lose desired sharpness.

Regridding itself fails from time to time.

Describe available calibration data sets
Upload calibration data sets if available:
Describe available test data sets
Upload test data sets if available:
Describe ideal data for testing

Do you have current or future plans for collaborating with other researchers?
Is there a manual available? Yes
Upload manual if available: Media:Snac.pdf
Model website if any
Model forum / discussion board

This part will be filled out by CSDMS staff

OpenMI compliant No but possible
BMI compliant No but possible
WMT component No but possible
PyMT component
Is this a data component
Can be coupled with:
Model info
Nr. of publications: 3
Total citations: 100
h-index: 2
m-quotient: 0.12
Qrcode SNAC.png
Link to this page




Nr. of publications: 3
Total citations: 100
h-index: 2
m-quotient: 0.12

Featured publication(s)YearModel describedType of ReferenceCitations
Choi, Eun-seo; Lavier, Luc; Gurnis, Michael; 2008. Thermomechanics of mid-ocean ridge segmentation. Physics of the Earth and Planetary Interiors, 171, 374–386. 10.1016/j.pepi.2008.08.010
(View/edit entry)
2008 SNAC
Model overview 68
Choi, Eunseo; Buck, W. Roger; 2012. Constraints on the strength of faults from the geometry of rider blocks in continental and oceanic core complexes: RIDER BLOCKS AND FAULT STRENGTH. Journal of Geophysical Research: Solid Earth, 117, n/a–n/a. 10.1029/2011JB008741
(View/edit entry)
2012 SNAC
Model application 32
See more publications of SNAC



Input Files

Output Files