Featured Image: Mount Etna, an active volcano in Italy. Credits to cattan2011
Introduction
Volcanoes vary greatly in their activity, with some volcanoes erupting very often (for example, multiple times a year), and other volcanoes only erupting every few hundred years or much, much more.
There are three categories which roughly indicate the level of a volcano’s activity:
- Active – a volcano which is erupting or has recently erupted, and is likely to do so again in the future.
- Dormant – an inactive volcano which hasn’t erupted for a very long time but is nonetheless likely to erupt in the future.
- Extinct – an inactive volcano which is unlikely to erupt in the future.
Let’s learn the difference between active, dormant, and extinct volcanoes in more detail, coupled with examples of volcanoes in each category of activity.
Active volcanoes
An active volcano is a volcano that is currently erupting or has erupted recently, and is likely to erupt again in the future.
The next long paragraph highlights what makes a volcano active. Skip it if you don’t really care!
Volcanologists generally might consider a volcano to be active if it has erupted at least once in the last 10,000 years (Holocene Epoch). Some volcanoes are obviously active. But other volcanoes which have indeed erupted in the last 10,000 years but have not erupted recently (for example, in the last a few hundred years) or have only erupted a few times in this timeframe might instead be classified as dormant. This is especially true if the volcanoes are located in active areas, where frequent activity is expected. Ultimately, it depends on each specific scenario whether or not a volcano should be considered active.
There are around 1400 volcanoes which have erupted over the last 10,000 years, many of which are indeed active today.
The Ring of Fire in the Pacific Ocean is a hotspot for volcanic eruptions (along with earthquakes), and so, lots of active volcanoes are situated along it.
Around 500 million people live near active volcanoes – over 6% of the world’s population.
The level of safety of living near an active volcano depends on factors such as:
- How violent and ominous the volcano’s activity is
- How well the volcano is monitored
- The quality of evacuation procedures in case of an eruption
Below are three of Earth’s current most active volcanoes:
- Kilauea – a shield volcano (gently-sloped volcano) on the island of Hawaii, a US state. Its name means ‘spewing’ in the Hawaiian language, which refers to its frequent release of lava.
- Mount Etna – a famous stratovolcano (conical volcano) on the east coast of Sicily, an island region of Italy. The fertile volcanic soil supports extensive agriculture and there are vineyards and orchards on the volcano’s gentle slopes. Due to past devastating eruptions (for example, the 1669 eruption which killed around 15,000) and nearby population, Mount Etna has been put on the list of Decade Volcanoes (active volcanoes close to densely populated areas worth studying) by the United Nations.
- Piton de la Fournaise – a shield volcano in the east of Réunion island (a French overseas region and department) in the Indian Ocean. Located in Réunion National Park, this volcano erupts often enough for it to be a major tourist attraction on the island.
Dormant volcanoes
Dormant volcanoes are inactive volcanoes which are not actively erupting and have not done so for a long time (at least a few hundred years, but usually much longer). However, they are likely to erupt again in the future. Dormant volcanoes are just asleep!
Unfortunately, it can sometimes be hard to distinguish an extinct (dead) volcano from a dormant (inactive) one. Therefore, if a volcano is believed to be extinct but suddenly comes to life, it has actually been dormant the entire time.
Dormant volcanoes are very dangerous for the following reasons:
- A long period of inactivity allows pressure to build up in the volcano, so when it does activate and erupt, the eruption could be colossal and therefore catastrophic.
- They are unpredictable, especially when wrongly thought to be extinct. Dormant volcanoes are sleeping, and we don’t know and cannot predict when they will wake up. So, when a dormant volcano becomes active and erupts, this eruption is unexpected and at short notice, which means damage and devastation will more likely than not be greater.
An example of a previously dormant volcano suddenly returning to life and wreaking havoc is Mount Pinatubo in the Philippines. After being dormant for around 500 years, it erupted in 1991 and ended up as the second largest eruption in the 20th century. It killed 847 people (directly and indirectly) and caused $700 million worth of damage. Before 1991, few locals knew about Pinatubo, which added to the damage and devastation when it did erupt.
Anyways, some volcanoes which are currently considered to be dormant are:
- Mauna Kea – a volcano in Hawaii. A relatively well-known fact is that if measured from top to bottom and not from sea level, Mauna Kea would be 10,200 metres (33,465 ft) high and therefore be the tallest mountain in this way (taller than Everest).
- Mount Kilimanjaro – a volcano located in north-eastern Tanzania, Africa, which also happens to be the tallest mountain in the continent of Africa.
- Mount Hood – a stratovolcano in the US state of Oregon.
Extinct volcanoes
Extinct volcanoes are volcanoes which scientists believe are extremely unlikely to erupt again – they are dead (asleep forever). Normally, if a volcano hasn’t erupted in the last 10,000 years, it is said to be extinct, but once again, this depends on specific circumstances.
Volcanoes become extinct when they no longer have a magma/lava supply (their supply is cut off).
As already mentioned, volcanologists sometimes cannot tell whether a volcano is indeed extinct (dead) or just dormant (asleep). Dormant volcanoes are expected to erupt again in the future, but extinct ones are not expected to do so (the probability is very low).
Below are some examples of extinct volcanoes:
- Ben Nevis – the tallest mountain in the United Kingdom, standing 1345m (4413 ft) above sea level. It is in Scotland.
- Huascarán – a tall mountain in Peru that is 6768m (22,205 ft) high.
- Edinburgh Castle, a famous castle in Scotland, is situated on top of the remnant of a volcano that went extinct millions of years ago. Note: Edinburgh Castle is not the extinct volcano! How silly would that be? Of course, the volcano that was originally below is.
Conclusion
So, in this geographical blog post, you have learned about the three categories of volcanic activity: active, dormant, and extinct. Examples of each type of volcano by activity have also been provided.
If you think you will forget everything you just learned, just remember the very basics below.
In terms of activity:
- Active volcanoes are awake,
- Dormant volcanoes are asleep, and,
- Extinct volcanoes are dead.
Anyways, check out another similar post below if you want to expand your geography knowledge, and whatever you do next, good luck!
Great Geography 