P-wave Velocity of Marine Sedimentary Layers in the Northern South China Sea Continental Margin
Date Issued
2016
Date
2016
Author(s)
Yu, Kang-Hao
Abstract
P-wave velocity is an important physical property of marine sediments, it also plays an important role in seismic data processing. Traditionally, we obtain physical properties of marine sediments by direct measurements of cored samples, but most of such samples come from very shallow sediments beneath seafloor, except where samples from deep sea drilling investigation are available. In order to obtain P-wave velocity information of sedimentary strata at depth, seismic velocity analysis techniques are often used. This study presents a summary of P-wave velocities of the sediments in the Northern South China Sea (NSCS) continental margin. Data from 2-D multichannel seismic reflection surveys are analyzed, using velocity spectrum analysis (VSPEC) technique to derive interval velocities in marine sediments. Through careful VSPEC, we can build a velocity model along the seismic profile which reveals velocity variations in the study area. We establish the characters of P-wave velocities for 3 geological provinces in NSCS: continental slope, lower slope, and ocean basin. The characters of depth relationship are usually presented in the form of equations relating interval velocity V with one way travel time t. The following relations are established for each of the 3 geological provinces: in the lower slope of NSCS-: V=1511+2373.8×t-406.18×t^2; in the Northwest Subbasin of NSCS: V=1511+2111.2×t-146.77×t^2; in the continental slop area of NSCS: V=1511+2003×t-20.342×t^2. In addition, we compared our velocity analysis results with those derives from logging data of the ODP site 1148 located in the Northwest Subbasin of NSCS. At site 1148, four seismic horizons from Pleistocene to Oligocene can be recognized, and so are our results from VSPEC. The velocity information from core data are in consistent with the velocity information derived from seismic data in this study.
Subjects
Inactive continental margin of Northern South China Sea
Sound velocity
velocity spectrum analysis
velocity function
velocity analysis
SDGs
Type
thesis
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