Hi KTee :-)

The # chart you're referring to is basically just the experience level of the volcanic activity/eruption :-)...

So, for example, on a chart of 0-5, depending on the volcano, the experience level is rated from 0 to 5 based from the type of activity or eruption level, almost like a rating out of 5...

Minor activity is usually rated at #3 out of 5 on the charts whilst an eruption is usually rated #4 out of 5 indicating that the experience level is at a higher rate/number due to an actual eruption...

0 being no activity, 3 being moderate activity/eruption and 4-5 being high to very high activity/eruption...

I hope this explained it to you enough for you to understand! :-)...

Was curious on that myself until I looked through the data and started to recognise a pattern in the experience levels... then I realised what the numbers were all about...

Glad you like the thread

Take care