Table 18.

Table T18. A comparison of VSP check-shot data with depth estimates derived from physical properties and logging measurements.

VSP
depth
(mbsf) VSP TWT*
(ms) VSP TWT**
(ms bsf) Predicted
depth
(m) Error
(m)

121.1
3232.6
140.6
120.95
-0.05

146.1
3261.6
169.6
145.84
-0.26

176.1
3297.5
205.5
177.45
1.35

206.1
3330.7
238.7
207.58
1.48

236.1
3361.4
269.4
238.81
2.71

266.1
3393.7
301.7
267.00
3.90

296.1
3426.9
334.9
301.33
5.23

326.1
3458.2
366.2
331.48
5.38

356.0
3491.6
399.6
363.37
7.37

386.0
3522.8
430.8
393.05
7.05

416.1
3555.2
463.2
425.09
8.99

446.1
3586.7
494.7
455.90
9.80

476.1
3611.1
519.1
479.80
3.70

505.2
3648.2
556.2
517.55
12.35

536.1
3663.5
571.6
533.75
-2.35

566.2
3703.6
611.6
576.03
9.83

596.1
3734.5
642.5
608.90
12.80

626.1
3765.5
673.5
641.34
15.24

656.2
3785.9
693.9
662.94
6.74

686.1
3816.4
724.4
694.44
8.34

VSP depth (mbsf)	VSP TWT* (ms)	VSP TWT** (ms bsf)	Predicted depth (m)	Error (m)
121.1	3232.6	140.6	120.95	-0.05
146.1	3261.6	169.6	145.84	-0.26
176.1	3297.5	205.5	177.45	1.35
206.1	3330.7	238.7	207.58	1.48
236.1	3361.4	269.4	238.81	2.71
266.1	3393.7	301.7	267.00	3.90
296.1	3426.9	334.9	301.33	5.23
326.1	3458.2	366.2	331.48	5.38
356.0	3491.6	399.6	363.37	7.37
386.0	3522.8	430.8	393.05	7.05
416.1	3555.2	463.2	425.09	8.99
446.1	3586.7	494.7	455.90	9.80
476.1	3611.1	519.1	479.80	3.70
505.2	3648.2	556.2	517.55	12.35
536.1	3663.5	571.6	533.75	-2.35
566.2	3703.6	611.6	576.03	9.83
596.1	3734.5	642.5	608.90	12.80
626.1	3765.5	673.5	641.34	15.24
656.2	3785.9	693.9	662.94	6.74
686.1	3816.4	724.4	694.44	8.34

Notes: * = VSP transit time corrected for the geometry of the experiment, and converted to two-way traveltime (TWT) for direct comparison to the MCS data. ** = VSP transit time converted to two-way time below seafloor (bsf). Predicted depth is calculated from the velocity-depth function derived from physical properties and logging measurements.