UACE-21 Conference (21-24 June 2021) was online. 240 participants from 25 countries present about 200 scientific papers about last research in underwater acoustics. 56 students presentation were present at the conference.
Leif Bjørnø Student Award 2021 was granted to student from Israel, Erns Uzhansky, University of Haifa, Department of Marine Geosciences, for the contribution:
Estimating Seafloor Compressional Sound Speed in a Compacting Passive Margin Basin Settings Using Standard Multichannel Seismic Data
Abstract of the paper:
In this paper, we present methodology and results of estimations of seafloor compressional sound speed along with sound speed gradient in a compacting passive margin basin (offshore Israel) setting using standard multichannel seismic data (7200 m long array with 576 hydrophones). We use geo-acoustic inversion with three matching parameters: 1) compressional sound speed at the water-sediment interface c_0 , 2) constant velocity gradient K, and 3) thickness of the sub-bottom layer with a constant velocity gradient H_2. A nice feature of the proposed methodology is that c_0,K,H_2 affect travel-time curves differently, so there is only one set of parameters (c_0,K,H_2) that is fully satisfying the travel-time curves from experimental data. The model considered consists of a water layer with a velocity that varies according to the season of data acquisition, lying above a layer in which velocity increases linearly with depth. Estimated c_0 and K, assessed for bottom depths of 1000 – 1350 m, varied from 1500 to 1600 m s-1 and from 0.7 to 0.9 m s-1 per m, respectively, and tend to increase with bottom depth. It was also verified that there is no inter-dependence in the estimation of the different parameters. The proposed method allowed to make assessments of relatively low sound speed speeds at water-sediment interface, where conventional refraction-based methods are not applicable.