Sensing Earth and environment dynamics by telecommunication fiber-optic sensors: an urban experiment in Pennsylvania, USA

Abstract

Abstract. Continuous seismic monitoring of the Earth s near surface (top 100\u2009 m ),\nespecially with improved resolution and extent of data both in space and\ntime, would yield more accurate insights about the effect of extreme-weather\nevents (e.g., flooding or drought) and climate change on the Earth s surface\nand subsurface systems. However, continuous long-term seismic monitoring,\nespecially in urban areas, remains challenging. We describe the Fiber Optic\nfoR Environmental SEnsEing (FORESEE) project in Pennsylvania, USA, the first\ncontinuous-monitoring distributed acoustic sensing (DAS) fiber array in the\neastern USA. This array is made up of nearly 5\u2009 km of pre-existing dark\ntelecommunication fiber underneath the Pennsylvania State University\ncampus. A major thrust of this experiment is the study of urban geohazard and\nhydrological systems through near-surface seismic monitoring. Here we detail\nthe FORESEE experiment deployment and instrument calibration, and describe\nmultiple observations of seismic sources in the first year. We calibrate the\narray by comparison to earthquake data from a nearby seismometer and to\nactive-source geophone data. We observed a wide variety of seismic signatures\nin our DAS recordings: natural events (earthquakes and thunderstorms) and\nanthropogenic events (mining blasts, vehicles, music concerts and walking\nsteps). Preliminary analysis of these signals suggests DAS has the capability\nto sense broadband vibrations and discriminate between seismic signatures of\ndifferent quakes and anthropogenic sources. With the success of collecting\n1 year of continuous DAS recordings, we conclude that DAS along with\ntelecommunication fiber will potentially serve the purpose of continuous\nnear-surface seismic monitoring in populated areas.