# Surface wave magnitude scale

The **surface wave magnitude** (M _{S} , of English *surface wave magnitude* ) is a method for measuring earthquakes - magnitude . It is based on the investigation of the movement of the surface by Rayleigh waves with a period T of 20 ± 2 seconds.

In 1945 Beno Gutenberg developed the following dimensionless number for teleseismic surface waves:

The coefficients are:

- is the maximum horizontal movement of the surface measured on the seismogram in micrometers with a period T of 20 ± 2 seconds for the north-south or east-west components,
- the distance of the place of measurement from the epicenter measured in degrees and
- a calibration function as the inverse of a semiempirically determined relationship between and . In 1958 Charles Francis Richter established a table with values for .

Sergei Leonidowitsch Solowjow suggested in 1955 the use of the maximum soil particle velocity , which better reflects the seismic energy.

Today *'s scale* , known as the Moscow-Prague formula, was formulated by Vít Kárník in 1962 as:

This formula only applies to and earthquakes with a focus depth of 50 km or less.

The surface wave magnitude scale has a saturation at M _{S} = 8.5.

## source

- Peter Bormann: 3.2 Magnitude of seismic events . In: Peter Bormann (Ed.): New Manual of Seismological Observatory Practice NMSOP . revised edition. Deutsches GeoForschungsZentrum GFZ, Potsdam 2009, ISBN 3-9808780-0-7 , p. 30-31, 48 , doi : 10.2312 / GFZ.NMSOP_r1_ch3 .