GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 The frst manually revised catalog of micro- seismicity of Co. Donegal (Ireland): defning baseline seismicity in a region of slow lithospheric deformaton. F. Riva 1,2 , N. Piana Agostnet 2 , S. Marzorat 3 , C. Horan 4 1. School of Advanced Studies, University of Camerino, Camerino, Italy 2. Department of Earth and Environmental science, University of Milano-Bicocca, Milan, Italy 3. Osservatorio Nazionale Terremot, Isttuto Nazionale di Geofsica e Vulcanologia (INGV), Ancona, Italy 4. Geophysics Secton, Dublin Insttute for Advanced Studies, Dublin, Ireland INTRODUCTION Ireland is a region of slow lithospheric deformaton and at the present Co. Donegal, located in its northwestern part, is the only seismically actve area in Ireland, with an average rate of an event every 3–4 years in the range of magnitude between 2-3. Regions of slow lithospheric deformatons are characterized by a low seismicity rate and limited accumulaton and release of tectonic energy, leaving open the queston if such deformaton is ‘difusely’ accommodated along a wide fault system rather than clusterized along specifc faults. Co. Donegal is also the site of post-orogenic radiogenic granites partly exposed along the NW Atlantc coast and potentally buried at shallow depth in the eastern part of the study region. For this reason, the area represents a target for deep (0–5 km depth) geothermal investgaton (Goodman et al., 2004). Having a high quality of precisely located micro-seismicity is fundamental before the exploitaton of geo-resources for investgatng seismicity and rock physical propertes in actve tectonic and volcanic regions and for the defniton of a ‘baseline’ seismicity, required for a safe future exploitaton of georesource areas. For these two reasons, the fnal aim of our work is the precise locaton of both human-induced and natural micro seismic events of Co. Donegal, which could give new insights in the tectonic deformaton mechanisms and help to fnd out granite volumes characterized by micro-fractures suitable for fuid circulaton. METHODS The seismic data provided in this paper have been collected thanks to the SIM-CRUST project : ‘Seismic imaging and monitoring of the upper crust: exploring the potental of low-enthalpy geothermal resources of Irelan d’ (htps://sim-crust.dias.ie ). The SIM-CRUST project provided a seismic network composed of 12 statons installed and maintained in Co. Donegal from August 2012 to June 2015 with the inter-staton distance between 5 and 20 km. All statons were equipped