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. 2017 Nov 10;7:15296. doi: 10.1038/s41598-017-15499-y

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© The Author(s) 2017

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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Seismic signal related to subway activity. (a) Envelope of the vertical acceleration for the interval 19:00–24:00 UTC (21:00–02:00 Local time) from Thursday to Sunday, filtered in the 20–40 Hz (black line) and the 0.008 and 0.05 Hz (red line) bands and decimated to 1 sample every 10 seconds. Late service during Friday and Saturday nights are identified by a box. (b) Envelope of acceleration filtered between 0.008 and 0.05 Hz and decimated to 1 sample every 10 minutes. Friday and Saturday nights are identified with orange and red arrows and clearly differ from the rest of the week. Large peak on day 01/09 correspond to a 7.0 earthquake with epicenter in New Zealand. Other peaks are related to local noise sources.