Train Traffic as a Powerful Noise Source for Monitoring Active Faults With Seismic Interferometry

Abstract

Laboratory experiments report that detectable seismic velocity changes should occur in the vicinity of fault zones prior to earthquakes. However, operating permanent active seismic sources to monitor natural faults at seismogenic depth is found to be nearly impossible to achieve. We show that seismic noise generated by vehicle traffic, and especially heavy freight trains, can be turned into a powerful repetitive seismic source to continuously probe the Earth's crust at a few kilometers depth. Results of an exploratory seismic experiment in Southern California demonstrate that correlations of train‐generated seismic signals allow daily reconstruction of direct P body waves probing the San Jacinto Fault down to 4‐km depth. This new approach may facilitate monitoring most of the San Andreas Fault system using the railway and highway network of California.

The 2020 coronavirus lockdown and seismic monitoring of anthropic activities in Northern Italy

“…Seismic data recorded during the lockdown might be particularly useful in identifying sources of anthropic noise, which could be employed by geophysicists, after the lockdown, e.g. to characterise the upper subsoil by cross correlation of ambient signal 23,24 .…”

COVID-19 lockdown and its latency in Northern Italy: seismic evidence and socio-economic interpretation

“…Previous studies revealed that the noise generated by human infrastructures can be clearly observed at distances larger than 10 km, nevertheless subsurface properties may significantly impact on the distance over which noise propagates 16 , 17 . Since the average interstation distance is around 32 km (figure S2 ), values at specific sites are indeed representative of the average noise level in a broader area around the observation point, especially where the density of stations is higher and the characteristics of noise are similar.…”

Temporal changes in anthropogenic seismic noise levels associated with economic and leisure activities during the COVID-19 pandemic

“…Furthermore, recently, it has become possible to use these anthropogenic noises for the visualization of near-surface structures since the recent development of permanent high-quality seismic networks and the development of techniques. Anthropogenic seismic noises, such as tra c and trains, were used to extract shear, compressional, or surface waves propagating between pairs of stations by computing crosscorrelation for visualization or monitoring 29,30 . Identifying dominant anthropogenic noise helps explore geophysics using passive seismic noise.…”