Mechanical waves travelling through Earth's surface or interior.
They are the main study subject of Reflection Seismology in Subsurface Exploration.
It can be a Surface wave propagating Earth's surface or a Body wave (p-wave and s-wave) propagating through Earth's interior.
See also
Natural Science / Geoscience / Subsurface Exploration / Reflection Seismology
[ Earth's Structure ][ Geology ] [ Seismic Waves ]
[ Surface wave ][ Body wave ][ p-wave ][ s-wave ]