Ongoing volcanic eruptions are often well visible on satellite images due to the clouds of ash and steam emitted by the eruption. In Kamchatka during winter you can also usually well identify recently active volcanoes even after the eruption ended due to the winter snow being darkened by falling ash where it was carried by the wind.
The following Landsat image from a few days ago well illustrates this.
On top you see an active eruption on the Karymsky with an ash plume and its shadow extending towards the northeast.
But you can also see extensive dark streaks of ash towards the southeast that were deposited earlier during the eruption with a different wind direction. Likewise for a second volcano further south – the Zhupanovsky.