Active Faults of Central America and the Caribbean
Central America and the Caribbean contain both rapidly-slipping faults and a large pulation, leading to great seismic hazard and risk. As part of the [CCARA] project, and to fill in a critical gap in the [GEM Global Active Faults][gaf] project, we have made a database of active faults in the region for use in seismic hazard analysis, earth science research, and education.
The database is a collection of fault traces in GIS vector formats, with associated metadata (attributes) for each structure describing the fault's geometry, kinematics, slip rates and other pertinent characteristics. The individual structures are mapped anew for this project based on interpretations of the literature and other datasets (e.g., digital topography data, earthquake catalogs, and GPS velocities). References for each structure are contained in the metadata, and a list of all references used is given in the repository.
|downthrown_side_id||string||direction of downthrown side||NE|
|average_rake||tuple||Slip rake of fault||(45,25,55)|
|strike_slip_rate||tuple||Strike slip rate on fault||(1.5,0.5,2.5)|
|dip_slip_rate||tuple||Dip slip rate||(1.5,0.5,2.5)|
|vert_slip_rate||tuple||Vertial slip rate||(1.5,0.5,2.5)|
|shortening_rate||tuple||Horizontal shortening rate||(1.5,0.5,2.5)|
|accuracy||integer||Denominator of map scale||40000|
|activity_confidence||integer||Certainty of neotectonic activity||1|
|exposure_quality||integer||How well exposed (visible) fault is||2|
|epistemic_quality||integer||Certainty that fault exists here||1|
|last_movement||string||Date of last earthquake||1865|
|name||string||Name of fault zone||Polochic|
|fz_name||string||Name of fault zone||Motagua-Polochic|
|reference||string||Paper used||Rogers and Mann, 2007|
|notes||string||Any relevant info||May be creeping|
|ogc_fid||integer||ID used by GIS||8|
There are three main data types used in the GAF attribute table,
tuple is a 3-[tuple] of real (floating-point or integer) numbers
representing continuous random variables such as slip rate. The tuple has the
(most-likely, min, max). In some instances where there is no estimated
uncertainty in the parameter of interest, the tuple may be simply given as
(most-likely,,); this is most common for the dip of purely strike-slip
faults. In typed databases it is actually represented by a string, so the
parentheses and commas will be preserved.
Rake is in Aki-Richards
convention. All slip rate fields except
shortening_rate describe the slip
rate or component on the actual fault, and are in magnitudes, i.e. are always
shortening_rate describes the horizontal contraction rate (heave)
of a fault (such as a GPS measurement); this is not the dip slip rate.
Extension across a fault is negative.
Integer is used as a categorical variable in this database, typically to
denote the relative epistemic uncertainty in a parameter.
1 is most certain,
2 is moderately uncertain, and
3 is highly uncertain. The other uses of
Integer types are for table indices in many constituent datasets, and in the
accuracy attribute which denotes the denominator of the map scale during
fault mapping and digitization; for example, a fault that was mapped in GIS at
a 1/40,000 (or 1:40,000) scale will have an accuracy of
Strings are for textual data.
The fault database is provided in a variety of GIS vector file formats. The version of record is the GeoJSON file, as changes in this file are tracked with git. The other versions are produced from this file via a script. QGIS users may use the GeoJSON file with the least friction; the GMT and KML formats work well in the GMT and Google Earth platforms, respectively, though metadata may be lost. The ShapeFile format suffers from truncation of attribute names and possibly text fields. ESRI users are suggested to use the GeoPackage format.
This project is funded by USAID as part of the CCARA project. A publication describing the work is forthcoming.
User reviews and revisions, and any additional feedback, are highly encouraged. Ideally contributions can be made by editing the GeoJSON file (hopefully in QGIS for maximum compatibility) and submitting a pull request. However we can work to accommodate most types of revision or addition. Please make an issue or email Richard Styron (richard dot h dot styron at gmail dot com).