Pagan Volcano made it into the activity report again!
So let’s see what our volcano is up to!

Global Volcanism Program: USGS Weekly Volcanic Activity Report:
Pagan Volcano:
Minor steam-and-gas plumes from Pagan were observed in satellite images during clear periods from 20 to 27 July. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Alright let’s go through this one and talk about what it means. This is some low level activity. “minor steam and gas plumes” this is generally due to degassing of the volcano. Magma has a lot of dissolved gases in it and as it rises to the surface those gases come out of solution and make bubbles and try to escape. A volcano can sit and de-gas happily and release lots of pressure and never explode. 

So how are these detected in satellite images? Well if the degassing volcano is mostly degassing water it can be very hard. From what I understand two images are taken within different bands of light. So like a red and blue band for example (that is not what it is I actually don’t know it was just an example ok!?) These images are differenced and the result can tell you if a “cloud” feature is mostly water (like weather clouds) or has other things in it (not weather cloud). It also says that these images were taken when it was clear, so it might just be visible spectrum and you can see a plume coming off of the volcano.

Ok now for a picture!

Here is a small plume from Pagan. Note the color. In general ash rich plumes (eruptions) are more gray. This is most likely degassing and lots of water vapor! 

Hope you enjoyed that look at Pagan Island!