Estimation of Basement Depth along the Sumiyoshi River in Kobe City

Travel Time Analysis of P-, S-, and SP-waves from

抄録

We estimated the basement depth in Kobe City from array records of aftershocks of the 1995 Hyogo-ken Nanbu earthquake. The array measurements were conducted along the Sumiyoshi River in Kobe City using 12 stations from north to south within a distance of about 2 km. Travel time analyses of initial P- and S-waves were made to obtain travel time residuals due to the sediments. We also obtained the travel time difference between S-wave and SP-wave (i.e., P-wave converted from S-wave) at the basement-sediment boundary. By compiling three travel time data sets, we estimated the distribution of the basement depth. The basement depth suddenly increases from 0 to 1 km within a distance of 1 km, and then the depth gently increases to the south.