A user-friendly approach to NDSHA computations

A web application has been developed, which offers a simplified approach to the computation of synthetic ground shaking scenarios, hiding behind a user-friendly graphical interface the great complexity of the computational engine. There is no steep learning curve to be followed before the user can generate a ground shaking scenario. This is particularly true for the design and execution of quick parametric tests in laterally homogeneous layered models, where the source or layer properties are varied, and the effects (or lack thereof) of their variation on the ground shaking can be immediately verified in the obtained scenarios. The simplest modeling executes in just a few seconds, with most of those seconds spent waiting for the scheduler to launch the job, and for the plotting routines to generate the PostScript vector images and to convert them into fair resolution raster ones. Under these conditions, it is a matter of minutes for civil engineers or city planners to obtain a first-order estimate of the seismic input expected for the next earthquake. Some of the computational tasks may become very demanding in terms of computational resources. A typical example is given by regional hazard computations applied to very large areas, more so if strong earthquakes with M > 8 have to be considered. For those strong events, the length of the source-site paths considered increases dramatically, and with it the number of synthetic seismograms to be generated.