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The Richter scale [1] (/ ˈ r ɪ k t ər /), also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale, [2] is a measure of the strength of earthquakes, developed by Charles Richter in collaboration with Beno Gutenberg, and presented in Richter's landmark 1935 paper, where he called it the "magnitude scale". [3]
First, the scale is logarithmic, so that each unit represents a ten-fold increase in the amplitude of the seismic waves. [12] As the energy of a wave is proportional to A 1.5, where A denotes the amplitude, each unit of magnitude represents a 10 1.5 ≈32-fold increase in the seismic energy (strength) of an earthquake. [13]
The cent is a logarithmic unit of measure used for musical intervals. Twelve-tone equal temperament divides the octave into 12 semitones of 100 cents each. Typically, cents are used to express small intervals, to check intonation, or to compare the sizes of comparable intervals in different tuning systems. For humans, a single cent is too small ...
Alpha Centauri (α Centauri, α Cen, or Alpha Cen) is a triple star system in the southern constellation of Centaurus. It consists of three stars: Rigil Kentaurus (α Centauri A), Toliman (α Centauri B), and Proxima Centauri (α Centauri C). [14] Proxima Centauri is the closest star to the Sun at 4.2465 light-years (1.3020 pc).
Logo of Eurocode 8. In the Eurocode series of European standards (EN) related to construction, Eurocode 8: Design of structures for earthquake resistance (abbreviated EN 1998 or, informally, EC 8) describes how to design structures in seismic zone, using the limit state design philosophy. It was approved by the European Committee for ...
EN 1069: Water slides of 2 m height and more. EN 1078: Helmets for pedal cyclists and for users of skateboards and roller skates. EN 1090: Execution of steel structures and aluminium structures (3 parts) EN 1092: Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated.
A census (from Latin censere, 'to assess') is the procedure of systematically acquiring, recording, and calculating population information about the members of a given population, usually displayed in the form of statistics. This term is used mostly in connection with national population and housing censuses; other common censuses include ...
In this model, the n-th century starts with the year that ends in "00" and ends with the year ending in "99"; [3] for example, in popular culture, the years 1900 to 1999 constitute the 20th century, and the years 2000 to 2099 constitute the 21st century. [4] (This is similar to the grouping of "0-to-9 decades" which share the 'tens' digit.)