h TSG = TSA + TAB + TBG = 2TSA + TAB ( x − 2h tan ic ) h =2 + v1 cosic v2 x 2h cosic = + v2 v1 = delay time Delay time ti t v1 v2 2 2h v2 – v1 x + -t = v2 v1 v ti x xcross x t = - + ti v2 x h= h v1 v2 v1v2 v22 − v12 ti t AG = x / V2 + δt g + δt a t BG = ( L − x) / V2 + δt g + δtb t AB = L / V2 + δt a + δtb Hagendoorn’s T- term T − = t AG − t BG = (2 x − L) / V2 + δt a − δtb Hagendoorn’s T+ term T + = t AG + t BG − t AB = 2δt g = z g cos(Θ c ) / V1 z g = T +V1 / cos(Θ c ) = T +V1V2 / V22 − V12 (a) Composite travel time-distance (b) Hagedoorns T- graph and (c) calculated Depths to a refractor