**5.3 Seismic methods**

Seismic tomography is a technique for imaging the Earth's interior with seismic waves produced by earthquakes or explosions. P and S waves and surface waves can be used for tomography models with different resolutions based on seismic wavelength, wave source distance, and seismometer array coverage [23].

Reflective seismology (or reflection seismic) is a technique of geophysics exploration that uses principles of seismology to approximation the properties of the Earth's interior from reflected seismic waves [24].

Seismic refraction is a geophysical standard governed by Snell's law of refraction. The seismic refraction method uses the refraction of seismic waves by rocks or soil deposits to characterize the subterranean geological conditions and geological building [24].

Seismic refraction is browbeaten in engineering geology, geotechnical engineering, and exploration geophysics. Seismic refraction traversal (seismic lines) are performed using a mixture of seismometers or geophones and a power source [24].

The procedures are based on the fact that seismic waves have different velocities in different types of soil or rocks. Waves are refracted when they cross boundaries between different types of soil or rocks. These methods allow the fortitude of general soil types and the estimated depth of stratigraphic boundaries or bedrock [24].
