Seismic reflection survey was conducted in Fushimi-Momoyama, Kyoto in November 1990. A linear array was spread across the extension of the Momoyama fault, which strikes from north to south at the eastern edge of the Kyoto basin. The length of the survey line was 1200m. A main aim of this survey was to investigate subsurface structure up to the depth of about 1km which possibly reveals the activity of the growth history of the Momoyama hill as well as the Momoyama fault. Seismic reflection survey is capable of imaging sedimentary layers because of its relatively short wavelength. A hydraulic weight dropping machine named “Yuatsu impactor” was used as a source apparatus. Through the data-processing by the CDP method and reverse time migration, the following results mainly were obtained.
(1) The basement and some sedimentary layers were identified. They are bent beneath the surveyline and their maximum dip is about 20 degrees to the west. The depth of the basement is about 300m beneath the Momoyama hill (east side) and about 600m in the Kyoto basin (west side).
(2) From the change of the dip in each layer, we found that the movement forming the Momoyama hill began less than 0.9 million years ago. Additionally, from the depth difference of each layer, the relative velocity of faulting since then is estimated at about 0.2m per 1 thousand years. This indicates that the activity of this movement is B class as noted in “Active Faults in Japan” (1991).
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