Emphasis was usually put on the horizontal acceleration factor, for the simple reason that ordinary structures have a built-in safety factor for the vertical component; that is, gravity.

Its revised edition publiCharles Francis Richterd in 1954 is considered a standard reference in the field. Science 83 (2147): 183–185. 173.

Charles Francis Richter (/ˈrɪktər/; April 26 1900 – September 30 1985) was an American seismologist and physicist. Richter is most famous as the creator of the Richter magnitude scale which until the development of the moment magnitude scale in 1979 quantified the size of earthquakes. The quote "logarithmic plots are a device of the devil" is attributed to Richter.