“…For linear models S will be an exact solution, because the definition of linearity implies linear combinations of solutions are also solutions, and the calculation is very fast once a unit-source database is constructed (containing solutions U i ). For this reason the unitsource approach is very popular for large-scale probabilistic hazard assessment (e.g., Burbidge et al, 2008;Li et al, 2016;Molinari et al, 2016;Davies et al, 2017;Davies and Griffin, 2020;Zhang and Niu, 2020). Unit-sources also greatly simplify tsunami source-inversion algorithms, including for early-warning applications, because techniques from linear-regression can be combined with tsunami observations to solve for s i (e.g., Tang et al, 2012;Fujii and Satake, 2013;Percival et al, 2014;Romano et al, 2016).…”