Time to count some very dangerous volcanoes. I've been through what could make a volcano dangerous and how I tried to classify volcanoes dangerous, developing a point system based on population, magma type, volcano type, and past large explosive eruptions. Looking at some recent articles on "dangerous volcanoes", my ranking comes to quite different conclusions. What my ranking comes down to comes down to which volcano has the greatest potential for population based on mass casualties, the style of eruption, and the potential for large explosive events.
I'll start with some honorable mentions that were left out of the top 10 (in increasing order of danger): Pululagua (Ecuador), Guntur, Gede-Pangrango and Semeru (Indonesia), Popocatépetl (Mexico), Colli Alban (Italy), Dieng Volcanic Complex and Tengger Caldera (Indonesia), Nyiragongo (DR Congo) and Merapi (Indonesia).
Here are the 10 worst volcanoes (with people living within 30 kilometers and 100 kilometers listed).
10. Santa María, Guatemala (1.25 million / 6.2 million):
This volcano might be best known for its more active vent, Santiaguito. It has a tendency to erupt explosively with the VEI 6 eruption as recently as 1902.
9. Taal, Philippines (2.38 million / 24.8 million):
Taal is a lake-filled caldera that produced four VEI 4 eruptions in the last 200 years and one VEI 6 eruption only about 5,500 years ago (VEI stands for Volcanic Explosivity Index, and tops at 7). Combine that explosiveness with plenty of water to increase potential explosive eruptions and the large population that could be affected by the ash, and you have a highly guarded volcano. Taal is monitored by PHIVOLCS, the Philippine volcano monitoring agency.
8. Coatepeque Caldera, El Salvador (1.2 million / 6.5 million):
Coatepeque is the first “black horse” in the top 10. It scores points for the eruption of rhyolite and dacite, both magmas prone to large explosive eruptions. It is also located in central El Salvador, so a large eruption could affect the capital of San Salvador along with the city of Santa Ana. Like Taal, it is a caldera filled with lakes that increases its potential danger by potentially increasing explosiveness or mudflows (lahars).
7. Corbetti Caldera, Ethiopia (1.2 million / 9.8 million):
Now this is a real volcano under the radar. The Corbetti caldera is located within an even older caldera and has produced pyroclastic cones (explosive eruptions of many volcanic debris) and obsidian flows, which means it has the correct eruption style and composition to potentially experience a large explosive eruption. Not much is known about Corbetti Caldera, making it difficult to limit its recent activity. However, it is close enough to Addis Ababa that a large ash-rich eruption could cause a humanitarian crisis.
6. Tatun Group, Taiwan (6.7 million / 9.8 million):
Like the Corbetti Caldera, Tatun is not a known volcano in a country that most people do not associate with volcanism. However, as I recently wrote, the Tatun Group has all the signs of a volcano that is still potentially active. It is also close to Taipei, so you might imagine that an eruption that produced another andesite dome could wreak havoc on the city, mainly from falling ash or mudflows.
5. Vesuvius, Italy (3.9 million / 6.0 million):
Do you really think Vesuvius wouldn't be in the top five? The volcano is one of the most dangerous on Earth thanks to its many explosive eruptions, and the city of Naples slowly creeping up its flanks. The fact that it's not at the top of this list (heck, it's not even the most dangerous in Italy) reveals just how dangerous the other volcanoes could be. Vesuvius has been silent since 1944, so we are full in the "complacency" phase, where most people do not remember the last eruption, it is never a good place where 6 million people could be affected by an eruption. explosive.
4. Ilopango, El Salvador (2.9 million / 6.7 million):
This is another caldera in El Salvador. But unlike Coatepeque, it has erupted in the last 200 years (1880 to be exact). Around 450 CE, Ilopango had a VEI 6 eruption that covered much of El Salvador in ash and toppled Mayan cities throughout the region. Today, San Salvador sits directly next to this lake-filled caldera, so significant danger from this caldera remains after 1,500 years.
3. Aira Caldera, Japan (0.9 million / 2.6 million):
The population around the Aira caldera might be lower than most of the top 10 volcanoes, but its frequent (Sakurajima) eruptions and history of large eruptions mean that it poses great danger to those 2.6 million people within the 100 kilometers. During the last 10,000 years of the Holocene, the Aira caldera had a half dozen VEI 4, 5 and 6 eruptions, so don't be fooled by the constant roar of small explosions from Sakurajima over the last decade.
2. Michoacán-Guanajuato, Mexico (5.8 million / 5.8 million):
What happens with the volcanic field of Michoacán-Guanajuato (M-G): the three population radius values are the same: 5.8 million. Yes, almost 6 million people live within 5 kilometers of this volcanic field that has produced pyroclastic cones generated by explosive eruptions. It has produced numerous VEI 3 and 4 eruptions in the Holocene from 1,400 vents. This means it hasn't had any major rashes, like some of the top 10. But the frequency, potential explosiveness and population in the widespread volcanic area make it a high risk.
1. Campi Flegrei, Italy (3.0 million / 6.0 million):
If you are the type of person who wants to care about Yellowstone, perhaps you should turn your attention to the Campi Flegrei. Not only is it a restless caldera with a more recent history of very large explosive eruptions, it is also smack in the middle of an area with over 6 million people ... and partially under the Bay of Naples. All of these factors mean that if the Campi Flegrei has a new onslaught of explosive eruptions, the risks could exceed those of any eruption in modern history. With that said, the last eruption (Monte Nuovo in 1538) was actually a fairly benign cinder cone.
Now, this ranking is highly subjective. There can be a multitude of ways to measure danger, so I'm sure people will not agree with this list. Volcanoes like Etna, Cotopaxi, Ruiz, Fuego, and more did not make the top 20, mainly because I chose to place an emphasis on the style and composition of magmatism.
The big important point here:
This list highlights the most “potentially dangerous” volcanoes based on their past behavior (mainly) and the potential for mass casualties. There will always be volcanoes that could only have a few thousand people living near it that could erupt and kill hundreds of people.
I think of eruptions like El Chichón in 1982 as a great example. The volcano wasn't even recognized as a threat until it erupted and killed about 1,900 people. It is unlikely that we will be able to eliminate all volcanic threats, and as the world's population grows, the danger posed by volcanoes that we can identify as dangerous (and those that we do not recognize as dangerous) will only increase. Funding volcanic research and monitoring in conjunction with emergency management organizations is the only way we can hope to protect ourselves from major volcanic disasters.
By Erik Klemetti
Original article (in English)