Seismicity Analysis with Spatial or Temporal Relation to the Deep Geothermal Project in Pohang, Korea

Abstract

We investigate seismic events between January 2016 and November 2017 that occurred in close vicinity to the deep geothermal project in Pohang, Korea. Using cross correlation analysis, we show that the epicenter of the M5.5 event is located within the stimulated reservoir volume and that the location of the hypocenter can be attributed to a rock volume that was stimulated by specific high-pressure injection campaigns. For our analysis we use data from locally installed networks (0-150m depth) and a deep borehole sensor at 2.3 km depth. However, we restrict our analysis to a few stations that were running during most of the 5 stimulation campaigns and establish a link between events using waveform similarity analysis. We derive dependencies between each of the five individual stimulations and to foreshocks of the M5.5 event which originated up to 10h before the mainshock and have similar S-P times. We show, that in the case of Pohang simple cross-correlation analysis can link the mainshock to a specific area within the stimulated reservoir volume.