Deployment of the Linear Array with Geophones on the Fault Zone of the 2016 Mw 5.5 Gyeongju Earthquake

After an earthquake with the moment magnitude 5.5 at a city of Gyeongju in South Korea on 12 September 2016, the public concern is raised about the safety of critical structures in surrounding region of the epicenter. The seismological and earth science communities aim to reveal earthquake source properties and fault structures using seismic array data recorded from various sizes of arrays including national permanent arrays and temporary arrays that were constructed after the 2016 Gyeongju earthquake. In particular, the densest broadband temporary array in the epicentral region named Gyeongju Hi-density Broadband Seismic Network provided seismic data to investigate subsurface structure. Furthermore, to better constrain detailed fault structure that is responsible for the 2016 Gyeongju earthquake, an additional seismic campaign of deploying low-cost 69 three-component geophones in a linear array was conducted in 2020. This linear temporary array of geophones is designed to cover the zone of aftershocks and deployed sub-perpendicular to the fault, closest to the mainshock, with a very dense spacing of 200 m. The array operated for one month from 17 November to 20 December 2020. An example of seismic waveforms, filtered at 2-100 Hz, of regional earthquakes shows clear P and S waves, and acquired waveform data during the deployment period can be usable for seismological research. This technical report contains information regarding the instrument, details about the deployment, and quality of the seismic waveforms.