Map Tools for EarthScope Science and Education: Strain Rate Models

Click on the movies below to see the deformation history in Southern California since 3 million years ago!!

Try out the interactive inquiry-based classroom exercises, based on these movies, using GIS and Google Earth!!

How the Models and Movies Were Generated

Strain Movies by Barbara Birkes
with mentoring by Bill Holt and Glenn Richard
Summer, 2004

The deformation simulations produced by summer REU student Barbara Birkes were generated on a low resolution 0.5° x 0.5° grid. That is, fault slip rates were used to estimate strain rates within these grid cells, and then the strain rates within these grid cells were interpolated with the continuous velocity field to yield the position estimates through time (see method description). The GPS data set produced by the Southern California Earthquake Center (SCEC3.0 velocity) were also used to produce the strain rate estimates in each time step (see method section). The movies produced by REU student Beth Ann Bell were produced on a much higher resolution grid (0.1° x 0.1°) and thus show finer detail.

Faults and Topography-3 Million Past to 3 Million Years Future

A model of the deformation field in Southern California from 3 million years past to 3 million years into the future. The time bar shows the age of the model positions. Note that North America is stationary and the Pacific plate is moving northwestward relative to North America. Note the rotation of some faults in the western Transverse Range region (clockwise). These faults are oriented at an angle to the direction of relative motion between the Pacific and North American plates, and have experienced rotation. Note that faults oriented parallel to the direction of relative motion between the Pacific and North American plates rotate very little or not at all. Shortening and uplift is occurring throughout many parts of the Transverse Ranges.

Velocity, Faults and Topography -3 Million Past to 3 Million Years Future

A model of the deformation field in Southern California from 3 Million years past to 3 million years into the future. The time bar shows the age of the model positions. Velocity vectors represent motions (magnitude and direction) of points in the deformation field relative to North America. These points represent the present-day positions of GPS sites that have been taken backward and forward in time (see method section) in order to generate the time evolved model.

Faults, Topography and Strain Axes -3 Million Past to 3 Million Years Future

A model of the deformation field in Southern California from 3 Million years past to 3 million years into the future. The time bar shows the age of the model positions. Principal axes of strain rate (bold vectors are the compressional principal axes and open arrows represent the extensional principal axes). Note that the grid upon which all calculations are performed is stationary, and topography points pass through the grid. This is analogous to a weather system, where the topography and motions represent the moving system and the principal axes represent a fixed point of measure (wind speed, or rainfall) on the ‘ground’. With this in mind it is possible then to watch a single ‘station’ (a principal axis of strain rate) and watch how it evolves as the ‘deformation front’ moves through.

3D Topography - Backwards into the Past

A 3-D perspective on the topography going 3 million years into the past.

3D Topography - Forward into the Future

3-D perspective on the topography going 3 million years into the future.

Dilatation

Time evolution of the model (faults) with the contoured dilatation rates. Red is compressional dilatation rate (negative), and blue is extensional (positive).

Shear

Time evolution of the model (faults) with the contoured shear strain rate magnitudes associated with pure strike-slip strain rate. Note that this plot shows where the strike-slip style of strain rates are concentrated within the plate boundary zone.

Data from Beth Ann Bell's Summer Project, Quantification of Past Tectonic Rates in Southern California, Formatted for Interactive Map Display by Glenn Richard

Google Earth KMZ files with Classroom Activities
These files enable the topographic and fault data to be viewed in Google Earth. The data also includes markers for cities that can be used to observe the movements of specific points on the crust.
ArcGIS Data with Classroom Activity
These files enable the topographic and fault data to be viewed in ArcGIS and other GIS software. The data also includes markers for cities that can be used to observe the movements of specific points on the crust. Google Earth Pro can also open shapefiles.

Strain Movies by Beth Ann Bell
with mentoring by Bill Holt and Glenn Richard
Summer, 2006

These models of finite strain were produced on a 0.1° x 0.1° grid. Only Quaternary fault slip rates were used to generate the finite strain models. The use of GPS in the finite strain models generated results with uplift rates that failed to match overall zones of inferred uplift (San Gabriel Range, San Bernardino Range).

Topography (gif)
Model of topography for the deformation model of Southern California from 3 million years ago ending in present-day. The time bar shows the age of the model values. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Topography - 6 million years (gif)
Model topography from 3 million years ago to 3 million years into the future. The time bar shows the age of the model values. Future projections show influence of small pull-apart regions that result in subsidence. No sedimentation is occurring in the model, and thus regions experiencing subsidence appear to drop below sea-level. It is likely that most of these regions would be areas of sedimentary fill. The model also does not account for the formation of new faults, and thus for regions of contraction the thrust faults cluster together into anomalously thin belts of uplift. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Topography p (gif)
Model topography from present-day to 3 million years into the future. The time bar shows the age of the model values. Future projections show influence of small pull-apart regions that result in subsidence. No sedimentation is occurring in the model, and thus regions experiencing subsidence appear to drop below sea-level. It is likely that most of these regions would be areas of sedimentary fill. The model also does not account for the formation of new faults, and thus for regions of contraction, the thrust faults cluster together into anomalously thin belts of uplift. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Topography p short (gif)
Model topography from present-day to 3 million years into the future. The time bar shows the age of the model values. Future projections show influence of small pull-apart regions that result in subsidence. No sedimentation is occurring in the model, and thus regions experiencing subsidence appear to drop below sea-level. It is likely that most of these regions would be areas of sedimentary fill. The model also does not account for the formation of new faults, and thus for regions of contraction, the thrust faults cluster together into anomalously thin belts of uplift. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Shear (gif)
Model shear strain rates (for pure strike-slip shear) through time. The time bar shows the age of the model values. These shear strain rates will be concentrated in regions where strike-slip related strains are highest. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Dilatation (gif)
Model dilatation strain rates (for pure strike-slip shear) through time. The time bar shows the age of the model values. These dilatation strain rates will be concentrated in regions where there is either a component of crustal shortening and crustal thickening (negative values) or crustal extension and crustal thinning (positive values). Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Finite Erosion (mov) Finite Erosion (gif)
. Finite erosion (kilometers) for the deformation model of Southern California from 3 million years ago ending in present-day. The time bar shows the age of the model values. The erosion is calculated by assuming that erosion rate is proportional to crustal thickening rates, calculated from the strain rate model (see model description). We assume that one half of the uplift volume that would result from crustal thickening, assuming Airy isostasy, is removed through erosion. Thus, the figure of finite erosion shows the most material removed where contraction rates (or crustal thickening rates) are highest. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Erosion (gif)
Instantaneous erosion values (blue is removal of material in meters) through time, from 3 million years ago ending in present-day. The time bar shows the age of the model values. Negative erosion values were not used to influence topography predictions. The erosion is amount that has occurred over a 50,000 year time interval. To get erosion rates, divide values by 50,000 years. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Finite Uplift (mov) Finite Uplift (gif)
Finite uplift (kilometers) for the deformation model of Southern California from 3 million years ago ending in present-day. The time bar shows the age of the model values. The uplift of the surface is calculated by assuming that erosion rate is proportional to crustal thickening rates, calculated from the strain rate model (see model description). We assume that one half of the uplift volume that would result from crustal thickening, using Airy isostasy, is removed through erosion. The uplift represents the total distance that the surface has traveled relative to sea-level, or the geoid. Note that the overall uplift rate of the surface is diminished by erosion, but there is also an isostatic rebound effect associated with the removal of material (for uplifting regions only). The figure of finite uplift shows the highest values where contraction rates (or crustal thickening rates) are highest. The model also shows where basins are forming through influence of crustal thinning. Sediment loading is not taken into account. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Uplift (gif)
Instantaneous uplift values (blue is uplift, and red is subsidence in meters) through time, from 3 million years ago ending in present-day. The time bar shows the age of the model values. The uplift is amount that has occurred over a 50,000 year time interval. To get uplift rates, divide values by 50,000 years. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Finite Exhumation (mov) Finite Exhumation (gif)
Finite exhumation (kilometers) for the deformation model of Southern California from 3 million years ago ending in present-day. The time bar shows the age of the model values. The exhumation is calculated by assuming that erosion rate is proportional to crustal thickening rates, calculated from the strain rate model (see model description). We assume that one half of the uplift volume that would result from crustal thickening, using Airy isostasy, is removed through erosion. The exhumation represents the total distance that the surface (at any given time) has traveled through the rock column. Note that the amount of exhumation is aided by erosion. Thus, the figure of finite exhumation shows the highest values where contraction rates (or crustal thickening rates) are highest as well as where erosion rates are highest. Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.

Additional Strain Movies by Beth Ann Bell
with mentoring by Bill Holt
Spring, 2007

Topography (mov)
Model topography from present-day to 3 million years into the future. The time bar shows the age of the model values. Future projections show influence of small pull-apart regions that result in subsidence. No sedimentation is occurring in the model, and thus regions experiencing subsidence appear to drop below sea-level. Most likely most of these regions would be areas of sedimentary fill. The model also does not account for the formation of new faults, and thus for regions of contraction, the thrust faults cluster together into anomalously thin belts of uplift. Right lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Shear (mov)
Model shear strain rates (for pure strike-slip shear) through time. The time bar shows the age of the model values. These shear strain rates will be concentrated in regions where strike-slip related strains are highest. Right lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Dilatation (mov)
Model dilatation strain rates (for pure strike-slip shear) through time. The time bar shows the age of the model values. These dilatation strain rates will be concentrated in regions where there is either a component of crustal shortening and crustal thickening (negative values) or crustal extension and crustal thinning (positive values). Right-lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Erosion (mov)
Instantaneous erosion values (blue is removal of material in meters) through time, from 3 million years ago ending in present-day. The time bar shows the age of the model values. Negative erosion values were not used to influence topography predictions. The erosion is amount that has occurred over a 50,000 year time interval. To get erosion rates, divide values by 50,000 years. Right lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Uplift (mov)
Instantaneous uplift values (blue is uplift, and red is subsidence in meters) through time, from 3 million years ago ending in present-day. The time bar shows the age of the model values. The uplift is amount that has occurred over a 50,000 year time interval. To get uplift rates, divide values by 50,000 years. Right lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.
Exhumation (mov)
Finite exhumation (kilometers) for the deformation model of Southern California from 3 million years ago ending in present-day. The time bar shows the age of the model values. The exhumation is calculated by assuming that erosion rate is proportional to crustal thickening rates, calculated from the strain rate model (see model description). We assume that one half of the uplift volume that would result from crustal thickening, using Airy isostasy, is removed through erosion. The exhumation represents the total distance that the surface (at any given time) has traveled through the rock column. Note that the amount of exhumation is aided by erosion. Thus, the figure of finite exhumation shows the highest values where contraction rates (or crustal thickening rates) are highest as well as where erosion rates are highest. Right lateral strike slip faults are thin red lines, left-lateral faults are thicker red lines, and thrust faults are thick red lines with ‘teeth’.

Modified September 27, 2007