Man‐induced low‐frequency seismic events in Italy

Unconventional seismic events in Italy are detected by scanning three years of continuous
waveforms recorded by the Italian National Seismic Network. Cross correlation of signal templates with
continuous seismic records has evidenced unusual events with similar low-frequency characteristics in
several Italian regions. Spectral analysis and spatiotemporal distribution of these events, some of which are
previously interpreted as tectonic long-period transients, suggest that they are not natural, but produced
by huge cement factories. Since there are at least 57 full-cycle cement plants operating in Italy, each
affecting areas of about 1250 to 2800 km 2 , we argue that significant portions of the Italian territory (23% to
51%) can be affected by this man-made noise. Seismic noise analyses, such as those used for microzonation
or crustal structure investigations, as well as data mining techniques used to retrieve anomalous transient
signals, should thus take into account this peculiar and pervasive source of seismic waves.