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| | Abstract | | Previous studies of beachrocks have been focused on the geochemistry. However, more knowledge on the chemical and physical properties are needed to elucidate its formation mechanism. In this study, a DC electrical survey and a seismic surface survey were conducted to detect the underground structure of the beachrocks in Yagaji Island, Okinawa, Japan. This is a first attempt at conducting multiple geophysical surveys to investigate Beachrock. In each survey, one survey line was set perpendicular to the seashore and two survey lines were set horizontal to the seashore. The results of each survey were shown in resistivity and seismic surface wave velocity sections. Furthermore, laboratory tests were conducted to measure the porosity, resistivity, and elastic wave velocity of the beachrock sample collected from this study site in order to estimate the effectiveness of the surveys. There was a superior correlation between both the sections and the date of the study site. Both surveys showed the vertical and horizontal extent, the resistivity, and the shear wave velocity of the rock. From these results, it is deduced that geophysical prospecting is extremely effective for studying the distribution of beachrocks. This paper shows the features of beachrocks in this area and the knowledge obtained from this study of geophysical prospecting for beachrocks. |
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