QuakeSim is a Web browser-based problem-solving environment that provides a set of links between newly available resources from NASA's Earth-observing systems, high-performance simulations, automated data mining, and more traditional tools. It's the first Web services-based, interoperable environment for creating large-scale forward models of earthquake processes. A Web services-based portal provides global access to geologic reference models of faults and fault data, simple analysis tools, new parallel forward models, and visualization support. QuakeTables, a database system for handling both real and simulated data, provides input for earthquake simulation tools using fault data. Later, it will include other types of earthquake data as well. This article describes our Web-based universal approach to heterogeneous earthquake databases using QuakeTables to demonstrate the design, development, and implementation challenges of incorporating solid earth science data sets in high-performance computing simulations.