An All-Source Green’s Function (ASGF) Database for Fast Predictions of Tsunamis Sourced anywhere in the India and Pacific Oceans

Abstract:

A new type of tsunami propagation database is introduced. The database consists of the All-Source Green’s Functions (ASGFs), which means that all the model grid points can be the potential tsunami source points and both the initial sea surface elevations and the initial water mass transports can be included in a source function. With the ASGFs, tsunami source regions no longer need to be restricted to a set of predefined blocks; the spatial resolution of the source functions no longer need to be limited by the sizes of the blocks; the resolutions can be as fine as the model grid spacing; the source function no longer needs to be only the initial sea surface elevations, which has been traditionally the case.

A numerical model for the linearized and depth averaged shallow water equations is used to calculate the ASGFs. The India, Pacific and Southern Oceans are taken as the model domain with a grid spacing of 5 minutes both in longitudes and latitudes. All the DART buoy locations are taken as the points of interest (POIs) for predictions, but other types of POIs can be added. The database can be used with a GPS-derived tsunami source function to instantaneously predict the arrival times and wave amplitudes of the tsunami at the POIs. It can also be used to assimilate the DART buoy data (or the like) to infer the tsunami source function. The inferred source function can be either used for tsunami predictions at non observational POIs in real time or for post-event studies on tsunami genesis mechanism.