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| | Abstract | | In Morioka City, it is known from the high density questionnaire survey at the time of several earthquakes that the seismic intensity differs within the narrow range of several kilometers in the city. In Aoyama and Motomiya areas of the city, we conducted microtremor observations at 48 points with a miniature array and ones at 47 points with a single seismograph, and estimated shallow S-wave velocity structures using microtremor H / V and phase velocities. 30 m average S-wave velocities (AVS) were calculated from estimated S-wave velocity structure models, and site amplification factors from engineering basements were calculated from AVSs. In Aoyama area, estimated S-wave velocities were slower at more points than those from the J-SHIS, and site amplification factors obtained by the microtremor measurements were larger at almost all points. Moreover, as a result of comparing with seismic intensity distribution map estimated by our previous questionnaire survey, it was confirmed that amplification factors were large at 1.6 to 2.5 on the east side where seismic intensities were large, and site amplification factors were small at 1.2 to 1.6 on the west side where the seismic intensities were slightly low. In Motomiya area, the S-wave velocities were generally high at 300 to 400 m / s, and site amplification factors were also low at 1.0 to 1.4. |
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