IODP Expedition 320-321: Pacific Equatorial Age Transect
Figure 6

A: VSP waveforms acquired in Hole U1337A. The direct arrival times are marked by red dots. The later event that converges toward the direct arrivals in the deeper receivers is a reflection from the top of the basaltic basement.

B: The direct arrival times in the VSP and the travel time of an acoustic pulse to the seafloor are interpolated to define a relationship between two-way travel time in seismic records and depth at Site U1337.  TWTT = two-way travel time.