Strong Motion Seismology
I had never worked on this subject when I was in Japan. It has started strangely only after my coming to France. However near-field ground motions are not yet quantitatively understood in its causality, mostly because of lack of recorded data and also because of complexity of earthquake source mechanics. Many things to do!
Existing methodologies are reviewed in Douglas and Aochi (Geophysics, 2008).
Review on methodology for calculating ground motions
Althouth the review by Douglas and Aochi (2008) is a decade ago, the situation is still valid. Empirical and statistical methods are used for practical applications. Numerical methods are able to provide the results in terms of calculation capacity, but the problem is how well we know the Earth, in its structure and process.