Facility Support: The Global CMT Project

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This award supports the Global Centroid-Moment-Tensor (CMT) Project, which provides analysis of global earthquake activity and a consistent, high-quality catalog of earthquake source parameters, the Global CMT Catalog. The objective of the Global CMT Project is to provide the best and most comprehensive record of global seismic strain release available. The basic earthquake parameters determined in a CMT analysis represent primary observations of the earthquake source process and provide valuable constraints for modeling and interpretation of global and regional tectonic activity. The CMT parameters allow description and prediction of global ground motion due to an earthquake. The CMT Catalog is the standard data base used in regional seismicity and tectonic studies, and the results are used in studies of stress changes and deformation due to earthquakes, as well as for research into complex and unusual seismic events, and for analyses of seismic hazard in the US and elsewhere. Educators at several levels integrate products from the CMT Project in a variety of activities. The CMT Project's current operational goal is to analyze all earthquakes with magnitudes greater than or equal to 5.0 occurring anywhere in the world. The results are disseminated via the project web site as well as by the IRIS Data Management Center and the International Seismological Centre; rapid analyses are also disseminated by email. The work supported by this award involves five main activities: (1) Systematic determination, with a three-month delay, of moment tensors for earthquakes of magnitude 5.0 and larger globally, and archiving of the results in the CMT catalog; (2) Rapid determination of moment tensors for earthquakes of magnitude 5.5 and larger globally and quick dissemination of the results; (3) Curation of the CMT catalog and continued improvements of the distribution mechanisms for this data base; (4) Routine detection and location of seismic sources using surface waves and distribution of a catalog of detected events; (5) Investigations of the quality of seismic waveforms from the Global Seismographic Network (GSN) and other seismic networks. This award will also support incorporation of an updated model of surface-wave dispersion in the CMT analysis and the development of a standard method for distributing earthquake detections obtained from surface-wave analysis.