Volcano Alerts is what is used to warn or educate people on what the current status of a volcano is. Many professional volcano research centers constantly monitor seismic activity, which is one of the easiest signs of a volcanic eruption. Gas, steam, or ash explosions usually signal that a volcanic eruption is imminent and that people in the surrounding area are in danger. A volcano that is spewing lava usually means that it is quietly erupting; if it gets to the point where some small steam or gas explosions are present or if lava is at high levels, then it becomes a violent eruption. To keep people away from danger and to inform people if their local volcano isn't restful is what the main point of these statuses are.
A volcano that is in a state of temporary slumber or isn't producing significant fumarolic activity usually is placed under the NORMAL status. Normal status could also mean that the volcano is dormant and isn't producing any activity, not even seismic; but if the volcano has no hints of previous activity for the past 800,000 years, then the volcano is considered extinct.
If seismic activity is above what its normal restful state is, then the volcano's status is raised to ADVISORY to give out a hint to people in the surrounding the area that their local volcano is becoming active. High fumarolic activity can also be present on the volcano.
Once the volcano has been reported to have produced a small ash cloud or lava flows, then the volcano awareness is raised to WATCH. Watch means that an eruption of the volcano is very possible, but an eruption isn't completely occurring. Also, people need to be aware if they are doing any recreational activity on or around the volcano. Seismic activity is usually very frequent but isn't typically at catastrophic levels.
If the volcano has been reported to have violently exploded or if lava flows are very large and dangerous, then the awareness is raised to WARNING. Warning means that the volcano is rather very close to erupting or is erupting. People living in the vicinity of the volcano need to consider evacuating as very dangerous threats are posed from it. Large ash or steam explosions, violent seismic activity, or large lava flows are just some typical things that occur on an erupting volcano.
If no present or current information is being provided from a local volcano research team, then the volcano's status is reduced to UNASSIGNED. Unassigned, means rather that the volcano has no current documentation on its seismic or fumarolic activity, or is not visible from ground level. Most seamounts are in this status until there is evidence that ash or lava is noticeable.
If no activity has occurred on a volcano for the past 800,000 years, then a volcano is considered EXTINCT. Extinct means the volcano is no longer being affected by magma or pressure from underneath the earth. An extinct volcano will never erupt again.