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 better understand core, mantle, and plate tectonic processes. Tomography is solved as an inverse problem. Seismic travel time data are compared to an initial Earth model and the model is modified until the best possible fit between the model predictions and observed data is found. Seismic waves would travel in straight lines if Earth was of uniform composition, but the compositional layering, tectonic structure, and thermal variations reflect and refract seismic waves. The location and magnitude of these variations can be calculated by the inversion process, although solutions to tomographic inversions are non-unique. Seismic tomography is similar to medical x-ray