I have said before that earth is nearing the end of about a 30 year cycle of increased tectonic activity. A hundred years ago it was Katmai in Alaska, 200 years ago it was Tambora. Will we have another huge volcanic eruption, or were the huge earthquakes off Indonesia and Japan the last major event for this cycle.
There are various monitoring stations on the peaks on the Big Island. The one where they do the CO2 sampling is supposedly DORMANT ~ yet the same station samples for RARE GASES seeping up through the volcanic mass immediately below.
There are a couple of other sites used for CO2 measurement ~ both 'down hill' from volcanic peaks ~ so the result is we don't know what surface measurements mean.
Methane is more my area.