5:15 PM - 6:45 PM
[HTT18-P06] Multi-channel surface wave survey at seafloor
Keywords:S-wave velocity structure, submarine surface wave survey, surface wave survey, dispersion curve, inversion
There is a growing need to investigate S-wave velocity structure under the seafloor. In recent years, microtremor array method is applied at seafloor to survey the one-dimensional velocity structure. We examined the applicability of seafloor surface-wave survey by an experiment in the actual sea area.
The experiment was carried out at the area with the water depth of 32-33 m in Suruga Bay. A 24-ch hydrophone array with a spacing of 1 m was deployed along the barge. Lead ingots were dropped from the 3 m above the seafloor to generate surface waves.
We obtained clear dispersion curves within the frequency range of 5-18 Hz calculated by observed waveforms. Because surface wave dispersion depends on the water depth, we performed the inversion analysis considering the water depth on the dispersion curves. Comparing the result with that by usual inversion analysis for onshore survey, the difference was significant.
Though there are some examples of surface wave surveys in shallower rivers, ponds, and tidal flats in Japan, this experiment provided valuable data of the survey in deeper sea.
The experiment was carried out at the area with the water depth of 32-33 m in Suruga Bay. A 24-ch hydrophone array with a spacing of 1 m was deployed along the barge. Lead ingots were dropped from the 3 m above the seafloor to generate surface waves.
We obtained clear dispersion curves within the frequency range of 5-18 Hz calculated by observed waveforms. Because surface wave dispersion depends on the water depth, we performed the inversion analysis considering the water depth on the dispersion curves. Comparing the result with that by usual inversion analysis for onshore survey, the difference was significant.
Though there are some examples of surface wave surveys in shallower rivers, ponds, and tidal flats in Japan, this experiment provided valuable data of the survey in deeper sea.