GIS-BASED ACTIVE FAULT MAP OF THE CARIBBEAN PLATE MARGINS

Active fault maps are key to many areas of the geosciences including earthquake seismology, seismic hazard assessment, earthquake engineering and petroleum exploration. The Caribbean plate is surrounded by largely submarine and active strike-slip and subduction plate boundaries. Some boundaries are up to 3000 km in length and 200 km in width and exhibit a multi-century record of magnitude 7 and 8 earthquakes. We present a pilot study using a geographic information system (GIS) to create a digital active fault map that can be layered with other forms of related data including population densities, road and infrastructure networks, GPS vectors, earthquake epicenters, major landslides, felt areas of major historical earthquakes, and run-up zones of historical tsunamis. A basic criterion for including faults on the map is the presence of a scarp affecting known or suspected Holocene sediments on the seafloor or onland. Submarine seafloor scarps are constrained using an extensive compilation of seismic profiles; onland scarps are detected using SRTM data along with traditional air photos. Using GIS, properties can be assigned to each fault segment (scarp height, scarp dip direction, age of deformed sediment, relevant seismic profile, paleoseismic information). These properties can be viewed by simply clicking on the feature. Such a map could be web-based and invite edits from a community of users in a "Wikipedia-type" effort to expand the database.