2017 Volume 58 Issue 2 Pages 94-101
In order to elucidate the behavior of a slope during earthquake shaking, we developed a new integrated sensor of accelerometer and inclinometer. The sensor was designed to need a small amount of electricity supply and be water- and pressure-proofed at a depth of 100 m so that it is installed into the boreholes in mountainous slope areas. Setting these sensors with a vertical array at a gravitationally deformed slope in the Shimanto accretionary complex in the Kii Peninsula, we have successfully recorded an earthquake with magnitude 6.5 on Apr. 1, 2016, which occurred in the source region of the Tonankai-earthquake. Using the obtained seismic waveform records, we estimated the amplification character of the slope. As a result, we found that the amplitudes in the frequency band of 1-6Hz are 2-7 times larger in the gravitationally deformed block （at 25m） than those in the fixed point （at 65m）. On the other hand, the amplitudes in the frequency band of 6-8Hz are 1.5-2 times larger on the surface, compared with those in the gravitationally deformed block and the bedrock.
