Figure 3. DAS recordings of footsteps on March 5, April 16, and June 4 (a-c) and traffic noise (e-g). Corresponding power spectra (d and h) from the seismograms above (a-c and e-g) were averaged over each subarray. Comparisons of construction-related seismic noise in the stay-at-home order (April 16, 2020) and in Phase Green (June 1, 2020). We selected DAS recordings at Ch 2100 next to the construction site (its location is indicated in Figure 1a). Raw DAS data and their time-frequency spectra maps on (i) April 16, 2020 and (j) June 1, 2020. The 20-Hz signal might be caused by the nearby air conditioner.