As an example, Figure 12.2 shows the bore hole log profile for the deep hole at pile 27 on the Dumbarton Bridge. Borehole Velocity Profile. We have had some preliminary results that indicate that the recording of weak motion is extremely valuable. Since the lithology at the bore holes is similar, we might expect the waveforms to be similar at each bore hole from the same earthquake. However, waveforms change significantly at the three deep bore hole sites.
Upper trace is west end, middle center, and lower east end of bridge, respectively.