Definify.com
Webster 1913 Edition
Seismal
{
Seis′mic
,Seis′mal
, }Adj.
[Gr.
σεισμόσ
an earthquake, from σείειν
to shake.] Of or pertaining to an earthquake; caused by an earthquake.
Seismic vertical
, the point upon the earth’s surface vertically over the center of effort or focal point whence the earthquake's impulse proceeds, or the vertical line connecting these two points.