This is a volcano on the island of Miyake in Japan. It has erupted, sending hot lava and ash into the air, a total of ten times. The time after one eruption until the next occurred was about twenty years in each case.
In 1983, black smoke came pouring out of Mt. Jinan and hot lava flowed down its side. The people on the island were very worried that Mt. Oyama, which is much larger, might also be preparing to erupt.
Remember that when an object is hot it gives off a special kind of light called infrared radiation. The infrared radiation, given off by the two mountains, was measured from space.
Engineers made a model of the mountain on paper and colored it according to its temperature. For example, the pink areas are the hottest, the browns and yellows and greens are much cooler. The people of the island were releaved to see that Mt. Oyama was cool. It was not going to erupt.
In this case, looking at the mountain in infrared was very important in deciding how to keep people safe.