Continuous passive seismic monitoring is carried out between September 2017 and December 2021 around the Theistareykir geothermal area located at the intersection between the active Northern Rift Zone and the active Tjörnes Fracture Zone in NE Iceland. This experiment, in addition to an extensive gravimetric monitoring survey, was conducted in the framework of the MicroGraviMoTiS project for a better understanding of the structures and behavior of the local geothermal system under exploitation and for further development of local and regional geothermal resources. 14 broadband stations (Trillium C-120s) recording at 200 Hz comprise the temporary network, that is installed to complement stations of the national seismological network of IMO and stations of Landsvirkjun, the National Power Company of Iceland. The stations were placed in and around the producing zone to primarily retrieve local natural and/or induced seismicity associated to the injection and production operations. The retrieved seismic data is also used for obtaining a representative 1D velocity model of the region, for computing a seismic ambient noise tomography, and for monitoring the system using coda wave interferometry techniques. Funding for this project is provided by the German Federal Ministry for Education and Research (MicroGraviMoTiS , BMBF, grant: 03G0858A), the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences and Landsvirkjun. Waveform data are available from the GEOFON data center, under network code 3P, and are embargoed until December 2025.