High-frequency ambient seismic noise changes for economic growth and COVID-19 pandemic

Abstract:

Ambient seismic noise represents ground responses to a composite effect of microseismic sources that include anthropogenic (cultural) sources such as traffic, construction, cultural activity, and industrial operations. Human activity is a major component to develop high-frequency ground vibrations that are recorded as seismic noises. The COVID-19 virus has a high infection rate, spreading fast in the world. Lockdown and stay-at-home actions have been taken in many countries. We investigate the influence of human-activity change on ambient seismic noises. We first analyze the ambient seismic noise changes for decades in major cities of 11 countries in diverse economic conditions. The seismic noises at frequencies greater than 2 Hz display diurnal periodicity that is associated with daily human activity. Anthropogenic sources dominantly control the daytime seismic noises. The annual seismic noise level follows the manufacturing gross domestic product (GDP). The noise level is proportional to economic growth. The noise levels increase fast in low GDP regions compared to high GDP regions. The noise levels in major cities increased by 14 to 111 % for 5-23 years. The high correlation between noise levels and GDPs may enable us to monitor the economic condition based on the seismic noises. The growing economy appears to enhance the Earth trembling. We then analyze the seismic noise changes during the COVID-19 pandemic in 7 countries including South Korea, China, France, Spain, Italy, UK, and USA. The human activities decrease with the number of daily confirmed cases. The high correlation between seismic noise level and community mobility suggests possible utilization of seismic noises for anonymous monitoring of human activities.