Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan.
Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan.
Sci Rep. 2021 Nov 5;11(1):20439. doi: 10.1038/s41598-021-00063-6.
Seismic ambient noise with frequencies > 1 Hz includes noise related to human activities. A reduction in seismic noise during the COVID-19 pandemic has been observed worldwide, as restrictions were imposed to control outbreaks of the SARS-CoV-2 virus. In this context, we studied the effect of changes in anthropogenic activities during COVID-19 on the seismic noise levels in the Tokyo metropolitan area, Japan, considering time of day, day of the week, and seasonal changes. The results showed the largest reduction in noise levels during the first state of emergency under most conditions. After the first state of emergency was lifted, the daytime noise reverted to previous levels immediately on weekdays and gradually on Sundays. This was likely because economic activities instantly resumed, while non-essential outings on Sundays were still mostly avoided. Furthermore, the daytime noise level on Sundays was strongly reduced regardless of changes on weekdays after the second state of emergency, which restricted activities mainly at night. Sunday noise levels gradually increased from the middle of the second state of emergency, suggesting a gradual reduction in public concern about COVID-19 following a decrease in the number of infections. Our findings demonstrate that seismic noise can be used to monitor social activities.
频率大于 1 赫兹的地震背景噪声包括与人类活动相关的噪声。由于为控制 SARS-CoV-2 病毒的爆发而实施了限制措施，全球范围内观察到地震噪声减少。在此背景下，我们研究了 COVID-19 期间人为活动变化对日本东京大都市区地震噪声水平的影响，考虑了一天中的时间、一周中的天数和季节性变化。结果表明，在大多数情况下，在第一次紧急状态下噪声水平下降最大。第一次紧急状态解除后，工作日白天的噪声立即恢复到以前的水平，而周日则逐渐恢复。这可能是因为经济活动立即恢复，而周日的非必要外出仍然大多避免。此外，第二次紧急状态主要限制夜间活动后，无论工作日是否发生变化，周日白天的噪声水平都大幅降低。第二次紧急状态中期以后，周日的噪声水平逐渐升高，这表明随着感染人数的减少，公众对 COVID-19 的担忧逐渐减轻。我们的研究结果表明，地震噪声可用于监测社会活动。
