GEM Global Mosaic of hazard Models
The Global Earthquake Model (GEM) Global Seismic Hazard Map (version 2018.1) depicts the geographic distribution of the Peak Ground Acceleration (PGA) with a 10% probability of being exceeded in 50 years, computed for reference rock conditions (shear wave velocity, V , of 760-800 m/s). The map was created by collating maps computed using national and regional probabilistic seismic hazard models developed by various institutions and projects, and by GEM Foundation scientists. The OpenQuake engine, an open-source seismic hazard and risk calculation software developed principally by the GEM Foundation, was used to calculate the hazard values. A smoothing methodology was applied to homogenise hazard values along the model borders. The map is based on a database of hazard models described using the OpenQuake engine data format (NRML); those models originally implemented in other software formats were converted into NRML. While translating these models, various checks were performed to test the compatibility between the original results and the new results computed using the OpenQuake engine. Overall the differences between the original and translated model results are small, notwithstanding some diversity in modelling methodologies implemented in different hazard modelling software. The hashed areas in the map (e.g. Greenland) are currently not covered by a hazard model. The map and the underlying database of models are a dynamic framework, capable to incorporate newly released open models. Due to possible model limitations, regions portrayed with low hazard may still experience potentially damaging earthquakes. The GEM Foundation plans to release future updates of this map on a regular basis as new information becomes available. Technical details on the compilation of the hazard and risk maps and the underlying models are available at
How to use and cite this work
Please cite this work as: M. Pagani, J. Garcia-Pelaez, R. Gee, K. Johnson, V. Poggi, R. Styron, G. Weatherill, M. Simionato, D. Viganò, L. Danciu, D. Monelli (2018). Global Earthquake Model (GEM) Seismic Hazard Map (version 2018.1 - December 2018), DOI: 10.13117/GEM-GLOBAL-SEISMIC-HAZARD-MAP-2018.1 This work is licensed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA):
This map is the result of a collaborative effort and extensively relies on the enthusiasm and commitment of various organisations and projects to openly share and collaborate. The creation of this map would not have been possible without the support provided by many public and private organisations during GEM’s second implementation phase (2014-2018). These key contributions are profoundly acknowledged. None of this would have been possible without the extensive support of all GEM Secretariat staff. The map was plotted using the Generic Mapping Tools software (Wessel et al., 2013).
This map was created for dissemination purposes. The information included in this map must not be used for the design of earthquake-resistant structures or to support any important decision involving human life, capital and movable and immovable properties. The values of seismic hazard in this map do not constitute an alternative nor do they replace building actions defined in national building codes. Readers seeking this information should consult national databases. This hazard map is the combination of results computed using 30 hazard input models covering the vast majority of landmass. These models represent the best information publicly accessible, and the GEM Foundation recognises their credibility and authoritativeness. This hazard map results from an integration process that is solely the responsibility of the GEM Foundation.