CHARACTERIZING SEISMIC NOISE FROM COAL MINING ACTIVITIES: EVALUATING POTENTIAL IMPACTS ON THE EINSTEIN TELESCOPE

The Einstein Telescope (ET) requires exceptionally low seismic noise conditions, particularly within the 1–10 Hz frequency range. This study investigates seismic noise generated by open pit lignite mining in the Euregio Meuse Rhine (EMR), focusing on the Hambach and Inden mines, to assess its potential contribution to the seismic noise conditions at the ET candidate site. The analysis combines near–far field measurements around mining machinery at Hambach, data from the temporary ZB seismic network across the Lower Rhine Basin (LRB), and surface and approximately 250 m depth recordings from the TERZ borehole station. Spectral analyses show that mining related seismic noise depends strongly on machinery type, operational stage, frequency content, and local site conditions. At Hambach, the Bucket Wheel Excavator (BWE) generated predominantly high frequency energy above approximately 10 Hz, whereas the Spreader produced broadband energy extending from about 7 to 100 Hz. In contrast, the Inden data revealed additional unkown low frequency signals between approximately 1 and 10 Hz that propagated over greater distances. Propagation analysis showed strong frequency dependent attenuation across the LRB, with BWE related noise decreasing to near background levels within approximately 1 km, Spreader related signals over even shorter distances, and the unidentified low frequency signals near Inden remaining detectable over several kilometres but strongly reduced within approximately 5 km. Apparent quality factors of approximately Q= 20–41 were consistent with strong attenuation in the unconsolidated sedimentary materials of the basin. No clear machinery related contribution was identified at the TERZ station either at the surface or at depth, but an induced seismic event associated with the mining region produced detectable energy between approximately 1 and 4 Hz at TERZ. Overall, the results indicate that direct mining operations at Hambach and Inden are unlikely to represent a significant contribution to the seismic noise conditions expected at the ET candidate site, although low frequency induced seismicity may require further consideration.