Fort Boise passive seismic water-recharge monitoring experiment

We will record three-component passive seismic noise data at Fort Boise, Boise, ID. These data will be used to monitor time-lapse changes in ground water. The Fort Boise area lies at the edge of the Idaho Batholith and the northern extent of the Western Snake River Plain -- the Boise Front. In this area there is ongoing geothermal resource extraction by the City of Boise. Ground water recharge in this region is critical to sustaining the resource. As more development occurs in the surrounding foothills, snow-melt runoff patterns begin to change. We will use seismic noise data to image the underground velocity structure during different time periods and determine changes related to ground water throughout a winter-spring melt run-off cycle. Seismic noise will be generated by traffic on the roads surrounding the site. We will arrange 62 three-component sensors to record noise from January 2018 to April 2018. We have geological knowledge and existing seismic reflection data for this area; we also have wells and drill logs that will be used to inform the seismic imaging and monitoring. With this background knowledge we have a very good initial model for this area, which will enable use to resolve small changes in the subsurface. We will also apply our new ambient noise full-waveform inversion code to these data. This research is important for passive-source surface-wave applications in urban areas. We will gain experience using these methods to investigate and monitor underground structures in urban settings.