The world experienced the beginning of the COVID-19 pandemic by the end of 2019 to the beginning of 2020. Governments implemented strategies to contain it, most based on lockdowns. Mexico was no exception. The lockdown was initiated in March 2020, and with it, a reduction in the seismic noise level was witnessed by the seismic stations of the national and Valley of Mexico networks. Stations located in municipalities with more than 50 000 people usually experience larger seismic noise levels at frequencies between 1 and 5 Hz, associated with human activity. The largest noise levels are recorded in Mexico City, which has the largest population in the country. The largest drop was observed in Hermosillo, Sonora; however, it was also the city with the fastest return to activities, which seems to correlate with a quick increase in confirmed COVID-19 cases. Mexico initiated a traffic-light system to modulate the re-opening of economic activities for each state. Therefore, since 1 June, noise levels have generally reflected the colour of the state traffic light. Furthermore, the reduction in the noise level at seismic stations has allowed identification of smaller earthquakes without signal processing. Also, people in cities have perceived smaller or more distant quakes.

中文翻译：

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COVID-19 限制对墨西哥地震噪声的影响

到 2019 年底到 2020 年初，世界经历了 COVID-19 大流行的开始。政府实施了控制它的策略，主要是基于封锁。墨西哥也不例外。封锁于 2020 年 3 月启动，随之，国家和墨西哥谷网络的地震台站见证了地震噪声水平的降低。位于人口超过 50 000 人的城市中的台站通常会在 1 到 5 Hz 的频率下经历更大的地震噪声水平，这与人类活动有关。墨西哥城的噪音水平最高，该国人口最多。在索诺拉州的埃莫西约（Hermosillo）观察到的下降幅度最大；然而，它也是恢复活动最快的城市，这似乎与确诊的 COVID-19 病例的快速增加有关。墨西哥启动了交通灯系统，以调节每个州重新开放经济活动。因此，自 6 月 1 日以来，噪音水平普遍反映了州交通灯的颜色。此外，地震台站噪声水平的降低使得无需信号处理即可识别较小的地震。此外，城市中的人们已经感觉到更小或更远的地震。