During May 2012, a productive, cooperative two-day meeting was held in Istanbul, Turkey for the research team of PEER’s Global Ground Motion Prediction Equations Program (Global GMPEs). The research team consists of experts in ground motion hazards representing all regions of the world including North America, South America, Europe, China, South Africa, Middle East, Australia and New Zealand.
In addition to hearing progress updates on all of the Global GMPEs tasks, the group spent one full day of the workshop discussing the preliminary selected global GMPEs for four tectonic regions that will be submitted to GEM at the end of the project. Each of the final models will include approximately 3 GMPEs and will represent the following types of seismicity:
- Shallow Crustal Regions
- Subduction Regions
- Stable Continental Regions
- Miscellaneous (including volcanic regions)
The purpose of such a model selection is for use by the GEM Foundation in their global seismic hazard analysis, rather than for regional and local seismic hazard studies.
Based on feedback from this meeting, final updates will be made to all the project tasks, and PEER will submit a final report to GEM in late 2012. More information on the project can be found at the Global GMPE website.
Ground Motion Prediction Equations (GMPEs), or “attenuation” relationships, provide a means of predicting the level of ground shaking and its associated uncertainty at any given site or location, based on an earthquake magnitude, source-to-site distance, local soil conditions, fault mechanism, and other parameters. GMPEs are used to estimate ground motions for use in both deterministic and probabilistic seismic hazard analyses.
The results of such hazard analyses are used for a wide range of applications such as: (1) site-specific seismic analysis and design of structures and facilities; (2) development of regional seismic hazard maps for use in building codes, financial estimation, etc.; and (3) social and financial loss estimation. Today, the most common Intensity Measures (IMs) used in GMPEs are peak ground motion values (e.g., peak ground acceleration, PGA; and peak ground velocity, PGV), and elastic response for various spectral ordinates.
What is GEM?
PEER has been funded to coordinate the Global GMPEs hazard component task as part of the Global Earthquake Model (GEM) initiative. GEM aims “to develop a web-based platform for risk assessment, which is based on a state-of-the-art, dynamic and open model for the assessment of seismic risk worldwide, catering for probabilistic assessment of earthquake occurrence, the resulting ground motions, and the impact these have on structures and populations in terms of damage, social and economic loss. When completed, the platform will allow for hazard and risk assessment, will include tools for analysis of socio-economic impact and will be powered by open source software.” More information at the GEM website.