Gridding data with faults in Surfer

To grid XYZ point data in text file data with faults in Surfer, you need to have an XYZ data file that you want to grid in addition to one BLN file that defines the fault traces. The articles Create a NoData Polygon or BLN file in Surfer and Create a BLN file to display multiple polylines in Surfer provide instructions for each of the available methods of to creating a BLN file of the fault traces. Please note, this article explains gridding with a fault in the Grid Data dialog only.

Be aware that faults can greatly increase the gridding time. We recommend that as few points as possible exist in the fault BLN file, preferably under 100 points. The more points you have in the fault file, the longer it will take to grid the data.  Note that there is not a way to specify direction of movement or amount of displacement along a fault in Surfer, as they aren't specifically geological faults.

Once you have a vector file that defines all the fault traces, you can grid the data with the fault file:

1. Click Home | Grid Data | Grid Data.
2. Click Browse in the Dataset 1 field, select your XYZ data file and click Open.
3. In the Grid Data - Select Data dialog, select the X, Y and Z data columns.
4. Choose a gridding method that supports faults (Inverse Distance to a Power, Minimum Curvature, Nearest Neighbor, or Data Metrics). I recommend starting with either Inverse Distance to a Power or Minimum Curvature.
5. Click the Next button to view the Grid Data - Options page.
6. On the Options page, expand the Faults section.
7. In the File Containing Fault Traces section, click the Change Filename folder icon, select the BLN file created above, and click Open.
8. Click Next.
9. Adjust the other settings as desired and then click Finish to create the grid file. The grid file will contain the fault data and you can use it to create maps in Surfer.

Note that any post processing of the grid file (e.g. using Grids | Resize | Mosaic or Grids | Edit | Assign NoData) will remove the fault information from the grid file.

Last updated August 24, 2020.