Table of Contents for GEON IDV web site Introducing the GEON IDV GEON IDV: Data Displays & Analysis Capabilities     GPS Velocity Vectors & Error Elipses     Earthquake Locations and Magnitude     Earthquake Focal Mechanisms     Seismic Anisotropy     Seismic Tomography     REM Global Seismic Tomography Data     Mantle Models' Tomography     Topography Data and 3D Relief Maps     Yellowstone Geophysics Example     Particle Plume Dispersion     Earth Strain Imagery     Seismic Ray Paths     GSRM Tectonic Plate Motion Vector Grids     Earth Strain Axes Download & Run the GEON IDV How to Use the GEON IDV: Basics     More Tips "True 3D" with the GEON IDV Data Online: The GEON Portal, and the UNAVCO Catalog GEON IDV Data Formats and Access Methods NetCDF Data for the GEON IDV UNAVCO's ASCII to NetCDF Data Converters

Earth Strain Axes Displays

You can display and investigate earth strain observations, using plots of "strain cross" symbols in the IDV. Any map region and map projection can be used, and the data can be displayed with maps, GIS shape files, and other kinds of geophysical data. Time animation is possible.

To create a data file that the GEON IDV can read, see GEON IDV Data Formats and Access Methods.
Note that strain observations are "point data."

To run the GEON IDV, see Download & Run the GEON IDV.

To load data in the GEON IDV and make displays see How to use the GEON IDV.

Variable names in NetCDF files for GEON IDV displays

To recognize this type of data in the GEON IDV and make correct displays, please use these variable names and metadata in your NetCDF file:

        double eps2_az(recNum) ;
                eps2_az:long_name = "azimuth of eps2, degrees clockwise from true north" ;
                eps2_az:units = "degrees" ;
        double eps2(recNum) ;
                eps2:long_name = "earth strain rate; most compressional eigenvalue of strain rate tensor; extension positive" ;
                eps2:units = "10-9 per year" ;
        double eps1(recNum) ;
                eps1:long_name = "earth strain rate; most extenional eigenvalue of strain rate tensor; extension positive" ;
                eps1:units = "10-9 per year" ;

Sample NetCDF and CDL files for this data type

Sample CDL file Strain_sample_pd.cdl (ascii)
Sample NetCDF file Strain_sample_pd.nc (binary)

Data on the UNAVCO GEON Server

You can access and display GPS data from the UNAVCO server.

In the IDV, to connect to the data, choose Data -> New Data Source -> From a Web Server; then in the window that appears, tab URL enter . Click the "Add Source" button.

Display Types

There is one type of display for this data type, the strain cross symbol shown in the sample figure below. You can control size or length scaling.

Sample Displays