This application computes deterministic response spectra for all GMMs supported by USGS hazard software. The application control panel provides selectors for all parameters used by the supported set of GMMs. Note that not all parameters may be used (or required) by a specific GMM. The application supports selecting multiple GMMs for comparison, or a single GMM in combination with multiple magnitudes or site classes (VS30). Use ctrl-click (Windows) or command-click (Mac) to select multiple GMMs; use shift-click to select a range of GMMs.