A sample of the (Fe + Al)/Si distribution as a volcanic activity index from May 16 to June 25 around Nishinoshima Island: (a) May 16-23, 2020, (b) May 24-31, 2020, (c) June 1-8, 2020, (d) June 9-16, 2020, (e) June 17-24, 2020, (f) June 25-July 2, 2020. It is mapped by applying the equation ((Fe+Al)/Si)=45.4(x)?13.3 to the SGLI data. From this, it can be seen that during this period, the distribution on the northeastern part of the island rises, and then the discoloration gradually progress...