Lg Waves 2


Lg Waves 2 :

Originally, short-period (1-6 seconds) large amplitude arrivals with predominantly transverse motion (Ewing et al., 1957). The maximum energy within the Lg-wave group propagate along the surface with velocities around 3.5 km/s which is close to the average shear velocity in the upper part of the continental crust. Lg waves are observed with frequencies up to 5 or 10 Hz and caused by superposition of multiple S-wave reverberations and SV to P and/or P to SV conversions inside the whole crust. The waves are observed only when the wave path is entirely continental and not disturbed by abrupt changes in crustal thickness or litho logical composition along major tectonic boundaries. As little as 20 of intervening ocean can be sufficient to eliminate the waves. See Kulhanek (2002, p. 336-337). For this and other such symbols used in seismic phase names see IS 2.1 in this Manual and Storchak et al. (2003 and 2011)

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