Editing Seismic refraction (section)

== Two horizontal layers==
[[File:refraction 2layers.png|800px|center|Two layers model.]]

i<sub>c<sub>0</sub></sub> - critical angle<br />
V<sub>0</sub> - velocity of the first layer<br />
V<sub>1</sub> - velocity of the second layer<br />
h<sub>0</sub> - thickness of the first layer<br />
T0<sub>1</sub> - intercept<br />
<br />
:<math>i_{c_{0}} = asin \left( {V_{0} \over V_{1}} \right) </math>
:<math> T = {2h_{0}cos(i_{c_{0}}) \over V_{0}} + {X \over V_{1}} = T0_{1} + {X \over V_{1}}</math>
:<math> h_{0}= {T0_{1}V_{0} \over 2cos(i_{c}) }</math>
:<math> h_{0} = {X_{cross_{1}} \over 2} \sqrt{{V_{1}-V_{0} \over V_{1} + V_{0}}}</math>