Ref: CTALK-2022-0073

Bedrock depth characterisation below public buildings with a geothermal interest using ambient seismic noise

Van Noten, Koen ; Zeckra, Martin

Talk presented at 3rd European conference on earthquake engineering and seismology on 2022-09-08

Abstract: Below several public buildings in Brussels (Belgium), one aims to transform the main heating source away from hydrocarbons towards shallow geothermal energy. The GeoCamb project investigates the geothermal potential of the Brabant Massif bedrock below Brussels. For each potential project, however, prospecting drilling and hydrogeological surveys costs remain high. With the use of three-component seismic nodes, either mounted on tripods installed on sealed surfaces or classic spikes coupled to the ground, we use passive seismic ambient noise methods to characterize bedrock variation around the geothermal open wells below the buildings of interest. Bedrock depth variation is studied by converting resonance frequency (f0), obtained from H/V spectral ratio analysis of ambient noise, to depth using a f0-to-depth power law relation specifically developed for Brussels. With additional ongoing urban array measurements, we aim to understand which impedance contrast the H/V curve represents in this urban setting. We currently hypothesize that the main H/V peak below Brussels illuminates the sediment-weathered bedrock contrast, rather than the weathered-intact bedrock interface deeper within the Brabant Massif.

Funding: B2/191/P1/GEOCAMB

The record appears in these collections:
Conference Contributions & Seminars > Conference Talks > Contributed Talks
Royal Observatory of Belgium > Seismology & Gravimetry

 Record created 2022-09-14, last modified 2022-09-14

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