How do you know if a volcano is not going to erupt anymore?

Answer 1

Criteria for Extinction Classification in VolcanologyWhen a volcano will not erupt anymore is known as extinct, however knowing when a volcano meets this criteria is very difficult to determine. There are several different factors that vulcanologist's look for when trying to make a determination like this. History of EruptionAny volcano that has erupted within the last 10,000 years is considered active, this time period is known as being a Holocene Volcano. These volcanoes are the most well known world wide and consist of a long list of volcanoes. When a volcano is active during the Holocene, it would still be considered active as the extremely long time it takes for a magma chamber to cool and harden under a volcano. See related links for more information on specific Holocene Volcanoes. Gas EmissionsAnother major thing that scientists look for is gas emission from the volcano. If the volcano is giving off carbon dioxide or sulfur dioxide than there is still at least molten rock below the volcano. If these things are not present however it does not mean that the volcano is extinct, there can simply be not enough pressure for the gasses to make it to the surface. Regional EarthquakesAlthough not all earthquakes near a volcano are related to things happening inside the volcano there are certain types of earthquakes that can only mean volcanic activity. These earthquakes called harmonic tremor mean that there is magma movement below the surface. If this is present it is very clear to scientists that there is activity occurring below the surface of the volcano and it is not extinct. Hydrothermal FeaturesAnother major thing that scientists look for are hydrothermal features, these would consist of either geysers or hot springs. If these are present around a volcano it indicates that there are very hot or molten rock close below the surface of the volcano and there more than likely is still a molten magma chamber. Weathering / ErosionErosion of a volcano is another good indicator of age, if there are glacial morrains on the volcano than it is more than likely going to be dated to around the times of the last ice age, which would mean that if those are the newest geologic features on the volcano than it has not been active in quite some time, possibly indicating that the volcano can be extinct. Combining the FactorsA volcano would more than likely be classified as extinct based off all these different types of evidence if the following things were noted to be true. There is no known history of eruption, at least in Holocene times. There is not any gas emission present anywhere around the volcano. There is no hydrothermal activity within the vicinity of the volcano. There is not a history of earthquakes in the immediate area of the volcano, and there is extensive glacial erosion of the volcano indicating that it has not been active since at least the last ice age.

Answer 2

Extinct, and dormant volcanoes can become active again, like Mt. St. Helens.

Answer 3

not erupting when the volcano is extinct or when scientist's say it probably wont any more that's how

Answer 4

It shows it in the

Answer 5

it's dead