Seismic code of buildings which survived the earthquake motion, recommended that the seismic ratio (seismic acceleration divided by the gravity acceleration) equal to 1/12 for the first floor and 1/8 for the floors above should be used in seismic design of buildings. The Committee proposed equivalent vertical forces much larger than the horizontal forces because vertical motion acted as impacts. This is believed to be the first known quantitative recommendation of design seismic forces in the history of seismic codes. The recommendation was adopted in Royal Decree No. 573 of April 29, 1915. The height of the buildings was limited to two
Seismic tomography frame to compare tomographic models to for iteration. Initial models had resolution of ~3000 to 5000 km, as compared to the few hundred kilometer resolution of current models. Seismic tomographic models improve with advancements in computing and expansion of seismic networks. Recent models of global body waves used over 10 traveltimes to model 10 to 10 unknowns. Seismic tomography uses seismic records to create 2D and 3D images of subsurface anomalies by solving large inverse problems such that generate models consistent with observed data. Various methods are used to resolve anomalies in the crust and lithosphere, shallow mantle, whole mantle,