Supervolcanoes: Past, Present and Future
Famous WWII Island Marks Undersea Volcanic Activity
What's a Supervolcano?
Fortunately, at the present, supervolcanoes are merely historical events that have left their marks on the surface of the earth. The last supervolcano eruption occurred about 27,000 on the North Island of New Zealand. The caldera of the supervolcano is today called Lake Taupo and the general area still remains seismic active.
Until recently, all known supervolcanoes have been found in terrestrial locales. However, a recent discovery (2018) of a very large underwater supervolcano, just off the southern coast of Japan, raises the likelihood that there may be other of these giants lurking on the ocean floor. This new discovery also raises the question that the timetable for the last supervolcano eruption may not be correct.
Measuring a Supervolcano
Despite their enormous size, there is a set standard by which a supervolcano is measured. The method is quantitative, for it consists of calculating how much ash and rock debris were thrown from the crater at the time of eruption. Any volcano emitting 240 cubic miles (1,000 sq. kilometers) or more of material is considered by earth scientists to be a supervolcano.
In general, all active volcanoes (past and present are rated on a scale of 1 through 8 with 8 being the most explosive. Not surprisingly, all supervolcanoes are valued as an 8. This rating system is called the Volcanic Explositivity Index (V.E.I.)
What Is a Caldera?
A caldera is a Spanish term that describes a large crater-like valley that forms after a volcanic eruption. Literally, the word translates as a kettle or cauldron. Furthermore, if you trace the word back to its Latin root, caldarium, you get a hot bath with the main emphasis being something hot or warm.
To an English-speaking geologist, a caldera is the bowl-shaped landform that appears at the summit of a volcano after it erupts and then collapses when the magma retreats back into the earth. A volcanic caldera may, on occasion, fill up with water and form a lake, as has happened at Crater Lake National Park in Oregon.
Today, scientists around the world are fascinated by several sites around the world, where it is obvious that sometime in the distant past, there was an extremely large volcanic event. Currently, there are six places, where supervolcanoes once occurred, but given our active geologic past, it is more than likely that other ancient sites will be discovered in the future.
At present, there are at least six recognized supervolcano sites, located around the world. Anyone interested in visited these places will be pleased to know that three are located in the U.S. West. Remains of one supervolcano can be found at Yellowstone National Park. Another, called the Calle Caldera, is located in north, central New Mexico and the third, named Long Valley is situated near Mono Lake on the California-Nevada border.
Elsewhere there are supervolcanoes located in southern Japan, on the Indonesian island of Sumatra and in New Zealand. Besides these six sites there are many other places around the world, where it is possible that a supervolcano may have also occurred in the past. Some of the more notable places can be found in Argentina, Chile, Siberia, Colorado, Italy and Indonesia.
Lake Taupo Today
Located in the center of New Zealand's North Island, the Lake Taupo supervolcano is now a water-filled caldera. The lake itself has been relatively quiet since the third century A.D., though the region is currently considered to be volcanically active with the last major volcano having occured in 1886 at nearby Mt. Tarawera.
Another Water-filled Caldera
Today, one of the most volcanically active places is the nation of Indonesia. Just within the last two hundred and fifty years two very explosive eruptions occurred at Krakatoa (V.E.I. 6) and Tambora (V.E.I. 7). Though not considered supervolcanoes, both these cataclysmic events created deadly tsunamis that killed thousands. Furthermore, each volcano emitted so much debris into the atmosphere that the weather patterns around the world were strongly affected.
To find evidence of a true supervolcano, one must visit present-day Lake Toba, which sits in a huge caldera that is 62 miles long and twenty miles wide. This spectacular body of water was created from the remnants of a monster volcano that exploded about 75,000 years ago.
An Ancient Caldera and Modern-day Active Volcano
In southern Japan not far from the city of Kagoshima, sits the remnants of another supervolcano. This particular one is called Aira and it last experienced a V.E.I. 8 eruption about 30,000 years ago. Today, the giant caldera is home to Bay and nearby sits the Sakurajima volcano, one of the most active in Japanand one of the most potentially dangerous due to the proximity of the Japanese city of Kagoshima.
Once a Supervolcano
Two American Supervolcanoes
Besides Yellowstone, the western U.S.is home to two additional supervolcanoes. Even so, these sites bear a fascinating geological record of enormous eruptions that occurred about a million years ago.
The first is Valle Caldera, which is situated in the Jemez Mountains of Northern New Mexico not too far from the town of Los Alamos. Once private ranch land, the large volcanic valley is now administered by the National Park Service. Today, the place is popular with skiers and hikers, who enjoy traversing the 13 mile wide valley that was forged about 1.25 million years ago.
Also in the western U.S. there is the Long Lake site, where a supervolcano occurred some 750,000 years ago. Unlike the Valle Caldera, scientists are watching this area for any signs of future eruptions, both big and small.
A Newly-discovered Underwater Supervolcano
The Kikai underwater supervolcano near southern Japan presents a whole new field of supervolcano research, as well as some something else to watch in the near futuure. Approximately 8,000 years ago a very large volcanic occurred in the undersea caldera that has recently been dubbed a supervolcano site.
Overall, this eruption released 500 cubic kilometers of material into the air. Though this is a huge volcanic, it does not reach the 1,000 cubic kilometer threshold, which defines a supervolcano. Fortunately, the last supervolcanic eruption to occur at this Pacific Ocean site happened about 80,000 years ago.
Supervolcano Title Page
A Cheesy TV Movie Attempts To Predicts the Future
Back in 2005, the BBC did a mash-up about a supervolcano erupting at Yellowstome.
"It's under Yellowstone. And it's overdue."
"A true story of global disaster... it just hasn't happened yet."
"This is a true story. It just hasn't happened yet."
"Scientists know it as the deadliest volcano on Earth. You know it...as Yellowstone."
"Beneath the beauty of Yellowstone Park, in the heart of America, a super eruption is stirring."
"Based on the predictions of leading scientists, this is the story of what could happen when Yellowstone erupts."
The above six statements are actually loglines, a cinematic term for catchy one-liners used to promote a feature-length movie. Although they all have a bit of scientific truth, geologic history of the Yellowstone supervolcano tells a slightly different story.
Grand Prismatic Spring at Yellowstone
A Brief History of the Yellowstone Supervolcano
According to geologists, the Yellowstone site has had three supervolcano eruptions in the last 2 million years with the last one occurring just a mere 640,000 years ago. Anyone familiar with mathematics will quickly realize that the next major eruption is due any day now, but that this prediction comes with a margin of error that could be as high as 10,000 years. Furthermore, readers should know that current conditions are not as favorable for a major eruption, as they were 700,000 years ago.
In conclusion, of the six major supervolcano sites mentioned here, only three are currently active. Though more supervolcanoes are almost certain to occur in the future, the likelihood of one happening in this century are minimal. Nonetheless, the calderas at Lake Taubo, Lake Tabo and Kagoshima Bay are hotspots, where smaller yet very destructive volcanoes that could take place in the next 50 years.
© 2018 Harry Nielsen