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Geothermal Energy

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Figure 9 | Geothermal Energy

Figure 9

From: Characterization of ambient seismic noise near a deep geothermal reservoir and implications for interferometric methods: a case study in northern Alsace, France

Figure 9

Evolution of the vertical component CCF waveform and the coda repeatability with local time. Left side: RITT-BETS CCFs, obtained from Monday to Friday, band-passed between 0.2 and 0.5 s and stacked separately for all the 5-min time slots of the day over the 2 years of available data. The stations are 2.8 km apart. The color bar corresponds to the amplitudes of the CCFs in arbitrary units. The thick black arrow indicates an enlarged part of the figure displayed in the closeup circle. Right side: temporal analysis of the coda (17 to 30 s of correlation lag time) performed separately for each hour of the day using a 30-day sliding window. The black curves show the median and standard deviation of the correlation coefficients measured between the coda and its reference. The red curve shows the standard deviation of the stretching coefficients measured before the drilling activities. We interpret these as the lowest detectable speed variations.

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