For the third time in less than two weeks, an orange alert in Yellowstone was issued, meaning the supervolcano is exhibiting heightened unrest with increased likelihood of eruption. Mary Greeley's video for June 9 gives Yellowstone earthquake information. According to Greeley, as of June 7, all of the Yellowstone borehole tiltmeters have been shut down, including the one at Norris Junction.
The most recent area of concern before the borehole shutdown was at Borehole B944 in Grant at Yellowstone.
The four-tiered Volcano Alert Level uses the terms “Normal, Advisory, Watch, and Warning” (from background levels to highest threat) to inform people about a volcano's status as follows:
- GREEN (Normal): Volcano is in typical background, non-eruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to non-eruptive background state.
- YELLOW (Advisory): Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
- ORANGE (Watch): Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway but poses limited hazards.
- RED (Warning): Hazardous eruption is imminent, underway, or suspected.
Volcano alerts notifications are issued for both increasing and decreasing volcanic activity and are accompanied by text with details about the nature of the unrest or eruption and about potential or current hazards and likely outcomes.