WebSims: A Web-based System for Storage, Visualization, and Dissemination of Earthquake Ground-motion Simulations

Synthetic time histories from large-scale three-dimensional dynamic rupture or ground-motion simulations generally constitute large data sets, which typically require hundreds of megabytes, gigabytes or even terabytes of storage capacity (see, e.g. , Olsen et al. 2008, 2009). For a seismologist analyzing rupture propagation or an earthquake engineer performing seismic hazard analysis, accessing large simulation output can be a tedious and error-prone procedure. For example, manual extractions of synthetic ground-motion records at a few sites of interest, or sliprate functions at desired locations on the fault, are subject to potential misinterpretation of site coordinates, units, or coordinate system orientation. If ground-motion synthetics or source-time functions are requested for a larger area (for example, to analyze site effects or rupture variability) additional problems may arise, such as bandwidth-related transfer delays, compatibility of storage devices used for dissemination, and time-consuming metadata assembly. Finally, the user may need to reformat the synthetics to apply post-processing steps, such as filtering or graphical display. To circumvent these problems we have developed a userfriendly Web application (WebSims) that allows fast plotting, processing, storage, and dissemination of rupture and groundmotion simulations. WebSims allows interactive access to large multidimensional gridded synthetic data sets. Since there is a unique time history at each grid point for each scenario, static storage of plot images for each point would require extraordinary amounts of disk space. Thus, clearly, plots must be created dynamically. WebSims uses software that allows on-the-fly extraction and plotting of synthetic seismograms via a Web browser. In terms of plotting and filtering features, but via different software, WebSims builds on a recent Web-based system used for validation of dynamic rupture simulations (Harris et al. 2009). However, an important difference from Harris et al. 's software is that WebSims is designed to manipulate large amounts of time series from simulations …