GuyotPhysics: Princeton University Campus as an Observatory for Seismic Background Noise

Abstract:

The analysis of seismic background noise has proven useful in studying local environments. Sources of background noise include oceanic phenomena, water-land interactions, fluctuations in temperature and atmospheric pressure, and human activity. Transportation, building engineering systems, and sporting events are among the many known sources of anthropogenic noise in urban settings. Anthropogenic noise has recently been widely investigated in the context of the 2020 COVID-19 pandemic. To reduce the spread of the coronavirus, governments across the world have enacted “stay-at-home”, “shelter in place”, or “lockdown” orders, calling upon people to stay at home whenever possible. These efforts have caused anthropogenic noise to decrease.

We investigate this global phenomenon in a local setting: the campus of Princeton University in Princeton, New Jersey. As research and classes transitioned to an online format and the state government issued a stay-at-home order, the number of people active on campus decreased relative to previous years. To study the seismic repercussions of this change in activity, we analyze data collected from a three-component broadband Nanometrics seismometer situated on a mechanically isolated slab in the basement of Princeton’s Guyot Hall. We identify earthquakes in the continuous records from 2018 to 2020 and remove them from our time series. We filter the remaining data to different frequency ranges, and we examine the difference in ground motion in 2020 relative to previous years to assess the degree to which our local observations are consistent with the regional, national, and global context.