Fig. 4

Cumulative distribution function (CDF) of basin size and population distributions for 9 cities during COVID-19 pandemic. a, CDFs of basin sizes in the morning rush hour for the 9 analyzed cities (Tokyo, Osaka, Nagoya, Fukuoka, Sapporo, Sendai, Hiroshima, Okayama and Kumamoto) during COVID-19 (from April 7 to June 30, 2020), where basin sizes are normalized by the mean basin size. We prepare human flow that accumulates weekday data from April 7th to June 30th, 2020, and calculate drainage basins. CDFs of the morning commuter rush hour are approximated by a power distribution of the same exponent \(-2.4\) as before the spreading of COVID-19 pandemic (Shida et al. 2020). b, The afternoon size distribution during COVID-19 pandemic. Comparing with the same plots for the year of 2016 before the pandemic shown in Fig. 8b, the distributions have longer tails deviating clearly for Tokyo and Sapporo. c, In the morning rush hours, CDFs of population of moving people in the basin follow a power distribution of exponents \(-1.2\), where the population in the basin is normalized by the average population in basins. This is again similar to that found in the non-pandemic times (Shida et al. 2020). d, The number of people moving in the basin during the morning rush hours is proportional to the square of the size of the basin