Pg, P
Pg, P : Travel-time curves at short distances (up to a few hundred km) for seismic sources in the Earth's crust usually consist of two intersecting straight lines; one with a velocity of about 6 km/sec at shorter distances and the other with a velocity of about 8 km/sec at greater distances. The former is attributed to direct P waves propagating through the crust and is designated as Pg, which stands for granitic layer. An alternative, older name has been P , which is no longer standard. For these and other such symbols used in seismic phase names see IS 2.1 in this Manual and Storchak et al. (2003 and 2011)