Seismic magnitude scales generally used for measuring magnitudes. Any skew in the spectral distribution can result in larger, or smaller, tsunamis than expected for a nominal magnitude. The tsunami magnitude scale, M, is based on a correlation by Katsuyuki Abe of earthquake seismic moment () with the amplitude of tsunami waves as measured by tidal gauges. Originally intended for estimating the magnitude of historic earthquakes where seismic data is lacking but tidal data exist, the correlation can be reversed to predict tidal height from earthquake magnitude. (Not to be confused with the height of a tidal wave, or "run-up", which is an intensity
Orders of magnitude (length) (10 m or 1.1 billion light-years). At this scale, expansion of the universe becomes significant. Distance of these objects are derived from their measured redshifts, which depends on the cosmological models used. To help compare different orders of magnitude, this section lists distances starting at 100 Ym (10 m or 11 billion light years). At this scale, expansion of the universe becomes significant. Distance of these objects are derived from their measured redshifts, which depend on the cosmological models used. Distances longer than 100 Ym Orders of magnitude (length) The following are examples of orders of magnitude for different lengths.