Seismic waves can be measured by seisometers. For example the 'San Andreas Fault Observatory at Depth' where seisomoters have been placed in an L-shaped bore hole accross the faultline at Parkfield.

Earthquakes can be measured by their magitude/intensity on the Richter Scale. The Richer Scale measues the energy released by the earthquake and is a logarithmic scale (an increase in magnitude of 1 = tenfold increase in energy released) .

Earthqukes can aso be measured by the Mercalli Scale which records the level of damage caused by an earthquake based on observations. For example, level 1 on th Mercalli Scale accounts fo earthuakes which are detected by seisometers but barely felt, whereas level 12 records earthqukes which cause extensive damage.