## Surface wave magnitude |

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The **surface wave magnitude** (**) scale is one of the ****GB 17740-1999**) for categorising earthquakes.^{[1]}

Surface wave magnitude was initially developed in the 1950s by the same researchers who developed the _{L} in order to improve resolution on larger earthquakes:^{[2]}

The successful development of the local-magnitude scale encouraged

Gutenberg andRichter to develop magnitude scales based on teleseismic observations of earthquakes. Two scales were developed, one based on surface waves, , and one on body waves, .Surface waves with a period near 20 s generally produce the largest amplitudes on a standard long-period seismograph, and so the amplitude of these waves is used to determine , using an equation similar to that used for .— William L. Ellsworth, The San Andreas Fault System, California (USGS Professional Paper 1515), 1990–1991

Recorded magnitudes of earthquakes during that time, commonly

The formula to calculate surface wave magnitude is:^{[1]}

where A is the maximum

According to GB 17740-1999, the two horizontal displacements must be measured at the same time or within 1/8 of a period; if the two displacements have different periods, weighed sum must be used:

where A_{N} is the north-south displacement in μm, A_{E} is the east-west displacement in μm, T_{N} is the period corresponding to A_{N} in s, and T_{E} is the period corresponding to A_{E} in s.

Other Languages

Deutsch: Oberflächenwellen-Magnituden-Skala

español: Magnitud de onda superficial

فارسی: بزرگای موج سطحی

հայերեն: Մագնիտուդ

Bahasa Indonesia: Kekuatan gelombang permukaan

italiano: Magnitudo delle onde superficiali

Bahasa Melayu: Magnitud gelombang permukaan

日本語: 表面波マグニチュード

suomi: Pinta-aaltomagnitudi

ไทย: ขนาดคลื่นพื้นผิว

中文: 面波震级