https://www.scientificamerican.com/article/volcanic-eruptions-detected-from-space/

Scientists are zooming out to get a more complete global view of volcanic eruptions—1.6 million kilometers out, to be precise. That is the distance to the Deep Space Climate Observatory (DSCOVR), a satellite originally conceived by former vice president Al Gore. Using an instrument onboard DSCOVR that can detect gases belched by volcanoes, researchers can now take snapshots of eruptions every one to two hours. Monitoring these events, which often spew ash that can trigger engine failure in airplanes, can help scientists quickly pinpoint potentially dangerous airspace.

Many of Earth's roughly 1,500 potentially active volcanoes are in remote areas, so it can be difficult to regularly study ongoing eruptions or identify new ones, says Simon Carn, a volcanologist at Michigan Technological University. “U.S. volcanoes are pretty well monitored, but elsewhere it's a different story,” Carn adds. “There's definitely a need for satellite monitoring.”