Researchers who study Earth’s movements say mandatory shutdowns of transportation systems and other human activities as a result of the coronavirus pandemic has resulted in a drop in what they call seismic “noise” around the world.An article published Tuesday in the scientific research journal Nature explains that human activity, such as moving vehicles and industrial machinery, can move Earth’s crust the way earthquakes and volcanic activity do. And researchers say the lack of such human activity in recent days has made a significant difference.Royal Observatory of Belgium seismologist Thomas Lecocq says vibrations caused by human activity have dropped by one-third since coronavirus containment measures were introduced in that country. Researchers at the California Institute of Technology reported a similar drop in the Los Angeles area, as did researchers in Britain.Nature reports the reduced human-generate “noise” has allowed scientists to get more accurate and sensitive readings regarding earthquake aftershocks in urban areas …