Fault Buffer Tool for QGIS

The Fault Buffer Tool is a QGIS plugin that creates uncertainty buffers around mapped fault traces based on literature-backed values. This tool supports geologists and engineers in visualizing and quantifying the uncertainty in fault locations for hazard assessment and scientific research.

Description

The Fault Buffer Tool allows users to define, justify, and plot well-informed uncertainty zones around mapped fault locations. It offers several approaches to uncertainty calculation based on peer-reviewed literature and geologic judgment.

Developed at Arizona State University, this tool aims to facilitate the use and advancement of fault location uncertainty analysis by the broader fault mapping community.

Features

• Multiple uncertainty calculation approaches:

  • General uncertainty (literature-based values)
  • Uncertainty with ranking based on:
    • Fault confidence (strong, distinct, weak, uncertain)
    • Primary/secondary classification
    • Simple/complex classification
  • Geologic judgment (custom uncertainty values)

• Fault type handling:

  • Strike-slip faults (symmetric buffers, 1:1 ratio)
  • Normal faults (asymmetric buffers, 1:4 ratio)
  • Reverse faults (asymmetric buffers, 1:2 ratio)

• Confidence intervals:

  • 50th percentile
  • 84th percentile
  • 97th percentile

Installation

1. Download the plugin ZIP file from the GitHub repository
2. In QGIS, go to Plugins → Manage and Install Plugins
3. Select Install from ZIP
4. Browse to the downloaded ZIP file and click Install Plugin
5. Once installed, the plugin will appear in the Plugins menu and toolbar

Usage

1. Prepare your fault map:

   • Create a fault line shapefile with appropriate attributes
   • Required attributes depend on your chosen uncertainty approach:
     • Quality (1-4): Confidence ranking (1=uncertain, 2=weak, 3=distinct, 4=strong)
     • PriSec (P/S): Primary or secondary fault classification
     • SimpComp (S/C): Simple or complex fault classification
     • Dip_direct (N,S,E,W,NE,SE,SW,NW): Fault dip direction for asymmetric buffers
     • Fault_type (S,N,R): Strike-slip, Normal, or Reverse
     • geo_unc: Custom uncertainty value (only needed for geologic judgment option)

2. Launch the plugin:

   • Go to Plugins → FaultBufferTool → Fault Buffer Tool

3. Set parameters:

   • Select the input fault line layer
   • Choose the output file location
   • Select the error approach:
     • General uncertainty
     • Uncertainty with ranking (select criteria to use)
     • Geologic judgment
   • Choose confidence interval (50th, 84th, or 97th percentile)
   • Select fault type handling method

4. Generate buffers:

   • Click OK to create the buffer shapefile
   • The new layer will be added to your map with appropriate styling

Input Requirements

• The fault shapefile can have a coordinate reference system of latitude and longitude (EPSG:4326) or the local UTM zone
• The plugin will output the buffer file in the local UTM zone

Example Attributes

Attribute	Description	Values
Quality	Fault confidence	4 (strong), 3 (distinct), 2 (weak), 1 (uncertain)
PriSec	Primary or secondary	P (primary), S (secondary)
SimpComp	Simple or complex	S (simple), C (complex)
Dip_direct	Fault dip direction	N, E, S, W, NE, SE, SW, NW
Fault_type	Type of fault	S (strike-slip), N (normal), R (reverse)
geo_unc	Custom uncertainty value	Integer value (in meters or feet)

Credits

Developers:

• Raswanth Prasath S V

Project Contributors:

• Chelsea Scott

Acknowledgments

We acknowledge support for this project from Pacific Gas and Electric, Co.

License

This plugin is licensed under GNU General Public License v2.0 or later.

Support

For issues, feature requests, or questions, please use the GitHub issue tracker.