Interactive web interface to the global strain rate map project

Chuck Meertens, Lou Estey, Corné Kreemer and William Holt

An interactive web interface allows users to explore the results of a global strain rate and velocity model and to compare them to other geophysical observations. The most recent model, an updated version of Kreemer et al., 2003, has 25 independent rigid plate-like regions separated by deformable boundaries covered by about 25,000 grid areas. A least-squares fit was made to 4900 geodetic velocities from 79 different geodetic studies. In addition, Quaternary fault slip rate data are used to infer geologic strain rate estimates (currently only for central Asia). Information about the style and direction of expected strain rate is inferred from the principal axes of the seismic strain rate field. The current model, as well as source data, references and an interactive map tool, are located at the International Lithosphere Program (ILP) "A Global Strain Rate Map (ILP II-8)" project website: The purpose of the ILP GSRM project is to provide new information from this, and other investigations, that will contribute to a better understanding of continental dynamics and to the quantification of seismic hazards. A unique aspect of the GSRM interactive Java map tool is that the user can zoom in and make custom views of the model grid and results for any area of the globe selecting strain rate and style contour plots and principal axes, observed and model velocity fields in specified frames of reference, and geologic fault data. The results can be displayed with other data sets such Harvard CMT earthquake focal mechanisms, stress directions from the ILP World Stress Map Project, and topography. With the GSRM Java map tool, the user views custom maps generated by a Generic Mapping Tool (GMT) server. These interactive capabilities greatly extend what is possible to present in a published paper. A JavaScript version, using pre-constructed maps, as well as a related information site have also been created for broader education and outreach access. The GSRM map tool will be demonstrated and latest model GSRM 1.1 results, containing important new data for Asia, Iran, western Pacific, and Southern California, will be presented.