A principal objective of the USGS response plan for volcanic activity is to communicate the
significance of monitoring measurements to local, state, and federal civil authorities because the
USGS has neither the authority nor the expertise to make decisions regarding the civil response
to an evolving crisis. The color-based rankings below replace an earlier alphabetic scheme (E, D,
C, B, A) to in which E-status designated weak unrest and A-status indicated an eruption was
likely. Whereas the alphabetic scheme was subject to misinterpretation by both the public and
the media, the familiar "traffic-light" associations more clearly communicate the level of unrest.

GreenRequires only routine monitoring
Background/typical conditions:
Up to 20 earthquakes with M<=3 per day
Uplift of the resurgent dome at about 1 inch per year

Weak unrest:
Increased number and (or) strength of small earthquakes
One or more M> 3 earthquake

Minor unrest:
An earthquake swarm including several M>3 quakes

Moderate unrest:
One or more M>4 earthquake
Over 300 earthquakes per day
No immediate risk

YellowWatchRequires intensified monitoring (emergency field HQ)
Intense Unrest:
An earthquake swarm including at least one M>5 quake
Evidence of deep magma movement as indicated by increased ground deformation
Downgraded to green 14 days after yellow conditions cease

OrangeWarningGeologic hazard warning issued by USGS to governor(s):
Eruption likely within hours or days:
Strong evidence of magma movement at shallow depth
Downgraded to watch 14 days after orange conditions cease

RedAlert:On-site monitoring and communication
Eruption underway
Downgraded to warning 1 day after eruption ceases