SSA 2019: Presenting the 2018 GEM Global Seismic Hazard Map and Global Active Faults Database

Richard Styron

This is the presentation I gave at the Seismological Society of America meeting in Seattle this spring.


The Global Earthquake Model (GEM) Foundation has the mission to promote earthquake resilience worldwide by creating and maintaining earthquake hazard and risk models, and associated datasets and software for probabilistic seismic hazard and risk analysis. In late 2018, GEM released the first versions of several of these products, including the Global Seismic Hazard Map, the Global Seismic Risk Map, and the Global Active Faults Database.

The Global Seismic Hazard Map (version 1.0- 2018) is based on a mosaic of 30 national or regional PSHA models developed by various institutions including the GEM Secretariat; each model is implemented in the OpenQuake engine (regardless of the original format). The map describes the spatial distribution of the peak ground acceleration with an annual probability exceedance of 10% in 50 years on an (almost) global equally spaced grid. It is the combination of 30 hazard maps computed for each individual model included in the mosaic. Unlike previous global hazard maps, the GEM Global Seismic Hazard Map (and underlying Model) is a dynamic, evolving product that will be updated regularly as the regional models are updated.

The GEM Global Active Faults database is similarly an evolving mosaic of regional catalogs of active fault traces and metadata describing the geometry, kinematics, slip rates, and other relevant parameters of each fault, and released as a vector GIS dataset. Fault catalogs developed for seismic hazard as well tectonic research have been included, with preference for hazard sources. New catalogs have been mapped by GEM for North Africa, Central America and the Caribbean, and northeastern Asia, with ongoing mapping in Canada and East Africa. Currently the database contains ~15,000 faults. Catalog assembly and harmonization are done programmatically whenever new data are available. These data products are free and released under a Creative Commons open license, and available at