Energy class – also called energy class K or K-class , and denoted by K (from the Russian класс) – is a measure of the force or magnitude of local and regional earthquakes used in countries of the

former Soviet Union The post-Soviet states, also known as the former Soviet Union (FSU), the former Soviet Republics and in Russia as the near abroad (russian: links=no, ближнее зарубежье, blizhneye zarubezhye), are the 15 sovereign states that wer ...

, and

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

and

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

. K is nominally the logarithm of seismic energy (in

Joules The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied. ...

) radiated by an earthquake, as expressed in the formula K = log E_S. Values of K in the range of 12 to 15 correspond approximately to the range of 4.5 to 6 in other magnitude scales; a magnitude 6.0 quake will register between 13 and 14.5 on various K-class scales. The energy class system was developed by seismologists of the

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

''Tadzhikskaya Complex'' nterdisciplinary''Seismological Expedition'' established in the remote Garm (

Tajikistan Tajikistan (, ; tg, Тоҷикистон, Tojikiston; russian: Таджикистан, Tadzhikistan), officially the Republic of Tajikistan ( tg, Ҷумҳурии Тоҷикистон, Jumhurii Tojikiston), is a landlocked country in Centr ...

) region of Central Asia in 1954 after several devastating earthquakes in that area. The Garm region is one of the most seismically active regions of the

, with up to 5,000 earthquakes per year. The volume of processing needed, and the rudimentary state of seismological equipment and methods at that time, led the expedition workers to develop new equipment and methods. V. I. Bune is credited with developing a scale based on an earthquake's seismic energy, although S. L. Solov'ev seems to have made major contributions. (In contrast to the "Richter" and other magnitude scales developed by Western seismologists, which estimate the magnitude from the amplitude of some portion of the seismic waves generated, an indirect measure of seismic energy.) However, proper estimation of E_S requires more sophisticated tools than were available at the time, and Bune's method was unworkable. A more practical revision was presented by T. G. Rautian in 1958 and 1960; by 1961 K-class was being used across the USSR. A key change was to estimate E_S on the basis of peak amplitude of the seismic waves – particularly, the sum of maximum P-wave and maximum

S-wave __NOTOC__ In seismology and other areas involving elastic waves, S waves, secondary waves, or shear waves (sometimes called elastic S waves) are a type of elastic wave and are one of the two main types of elastic body waves, so named because th ...

– within the first three seconds. As a result, K-class became a kind of local magnitude scale, similarly limited to local and regional earthquakes of about M 6.5 (K 15) or less, above which point it saturates (underestimates the magnitude). Rautian also developed a

nomogram A nomogram (from Greek , "law" and , "line"), also called a nomograph, alignment chart, or abac, is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a mathematical function ...

to simplify some of the calculations, and used a number of simplifying assumptions appropriate for the Garm region. That version is sometimes labelled K_R to distinguish it from other versions – K_F, K_S, K_FS, K_C, etc. – that have been adapted for the

Sakhalin Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh ...

, Kurile, and

Kamchatka The Kamchatka Peninsula (russian: полуостров Камчатка, Poluostrov Kamchatka, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and west ...

regions in the Far East. There are various formulas to convert K-class to other magnitude scales; these are usually specific to the regional network. M_(K) (or some variant) is sometimes used to identify magnitudes that have been calculated from a K value..

Notes

Sources

*. *. *. *. Draft English translation of the original Russian by the U.S. Air Force Foreign Technology Division, document FTD-TT-62-269/1+2. Armed Services Technical Information Agency document AD400507. *. *. *. {{DEFAULTSORT:Energy class Seismic magnitude scales Seismology measurement Seismology Logarithmic scales of measurement

See also

Notes

Sources