First, because many of
the earth's strong earthquakes are preceded within hours, days or
weeks by smaller earthquakes called foreshocks, this premonitory
seismic activity may well be related in some way to the non-seismic
precursors described above. Second, in principle, satellite-based
detection of seismic ground motions is possible, and in the future
there may be interest in developing such a technology to complement
surface-based observations.