[Steve Van Doorn]

SUMMARY OF VOLCANO ALERT LEVELS
http://volcanoes.usgs.gov/activity/alertsystem/index.php
http://volcanoes.usgs.gov/activity/status.php

[HerrBlucher]

First stage then would be yellow, right? A yellow alert being activity slightly above background? Yellowstone is normal green right now. I assume it is your interpretation of the data, and not the USGS’s, that indicates a potential yellow alert?