[Case Study] Earthquake Observation System for Detailed Ground Investigation

A seismic observation system has been established to monitor aftershocks using seismometers installed underground and on the surface, and to investigate ground amplification characteristics.

**Overview** ■Purpose: Earthquake Observation ■Category: Measurement Equipment ■Related Products: Measurement Units for Earthquake and Volcano Observation ■Scope of Provision: System Design, Complete Equipment Set, Installation and Adjustment **Background and Issues** At the Railway Technical Research Institute, during the main shock of the Kumamoto Earthquake in 2016, non-linear ground behavior was confirmed in the northern part of the Kumamoto Plain. The customer decided to conduct temporary earthquake observations at two locations, one in an urban area and the other in a mountainous area, to investigate detailed ground amplification characteristics. There were conditions that required the use of a high dynamic range seismometer, a local recording method, and the inability to secure commercial power supply at the mountainous observation site. **Provided System** For the underground and surface seismometers, we provided high dynamic range digital output servo accelerometers. At the urban observation point, a seismometer was also installed underground (borehole approximately 40m) for the continued investigation of ground amplification characteristics. At the mountainous observation point, where commercial power was not available, a solar-powered system was implemented. In addition to a controller to manage the seismometer, we provided a recording device that allows for easy data retrieval through external SSD exchange. This setup contributed to achieving high-speed sampling (1000Hz) while enhancing operational efficiency, despite being a local recording method.

Vibration and Sound Level Meter