You have full access to this open access chapter, Download reference work entry PDF
Definition
T he relationship of elastic longitudinal wave (Vp-waves) velocity to shear wave (Vs-waves) velocity or the relationship of elastic shear wave (Vs-waves) velocity to longitudinal wave (Vp-waves) velocity.
Characteristics
In engineering seismology, the velocity ratio Vp/Vs (TAU parameter) is considered as an indicator of the changes in stress state of rocks in the process of development of strong tectonic and volcanic earthquakes. It is established that deep fault zones, named gradiental zones, display rapid changes in the ratio Vp/Vs with a change of the anomalies’ sign (positive or negative). These can be considered as seismogenic zones. Relatively low values of Vp/Vs ratio indicate increases in activity in the magmatic chambers of volcanos during their activization. The ratio of Vp-waves velocity to Vs-waves velocity (Vp/Vs) is used in engineering seismology and engineering geology (Slavina et al. 2015).
The ratio of Vp-waves velocity to Vs-waves velocity (Vp/Vs) is used in engineering seismology and engineering geology. In engineering geology, the velocity ratios Vs/Vp and Vp/Vs аre used for definition of physic-technical characteristics of rocks. If the values of both ratios are known, it is possible to define dynamic modules of elasticity – Poisson’s ratio μ, the Young’s modulus E, and the shift modulus G. These characteristics are of interest at carrying out engineering surveys for construction. To define the Poisson’s ratio μ, it is necessary to know Vs/Vp or Vp/Vs ratios only; for definition of the Young’s modulus E and the shift modulus, G it is necessary to know also the density of rocks. For definition of static modulus necessary for engineering calculations, empirical ratios or special diagrams are used (Nikitin 1981; Bondarev 1997).
Cross-References
References
Bondarev VI (1997) Seismic method of definition of physic-mechanical properties not rocky soils. USMGA, Ekaterinburg
Nikitin VN (1981) Bases of engineering seismicity. MSU, Moscow
Slavina LB, Kuchay MS, Lichodeev DV (2015) Assessment of kinematic parameter TAU behavior as indicator of the pressure variation on the example of the results of observations on Kamchatka and Caucasus. “Problems of complex geophysical monitoring of the Far East of Russia”. On 27th Sept – 3rd Oct 2015, Petropavlovsk-Kamchatsky
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2018 Springer International Publishing AG
About this entry
Cite this entry
Zhigalin, A. (2018). Velocity Ratio. In: Bobrowsky, P., Marker, B. (eds) Encyclopedia of Engineering Geology. Encyclopedia of Earth Sciences Series. Springer, Cham. https://doi.org/10.1007/978-3-319-12127-7_289-1
Download citation
DOI: https://doi.org/10.1007/978-3-319-12127-7_289-1
Received:
Accepted:
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-12127-7
Online ISBN: 978-3-319-12127-7
eBook Packages: Springer Reference Earth and Environm. ScienceReference Module Physical and Materials ScienceReference Module Earth and Environmental Sciences