A supervolcano eruption can dramatically alter life on earth and can contribute to species’ mass extinction, according to a recent study. Scientists working at the National Center for Scientific Research (NCSR) in Grenoble, France said that a supervolcano can literally wipe out an entire civilization when it erupts. They also found out that supervolcanic eruptions do not need earthquakes as an external force to break open the Earth’s crust for magma to escape violently. Eruptions at this scale can also happen due to the buildup of pressure underneath the crust, they added.
The United States Geological Survey (USGS) defines a “supervolcano” eruption as one having expelled ash, pumice or lava deposits of greater than 1,000 cubic kilometers (240 cubic miles) or having an eruption equivalent to magnitude 8 on the Volcano Explosivity Index (VEI). When a supervolcano erupts, it is hundreds of times more powerful than a regular volcano eruption. Volcanic eruptions can cause “volcanic winters” because volcanic ash in the air can block out sunlight.
To put this in perspective, when Mount Pinatubo in the Philippines erupted in 1991, it ejected 5 cubic kilometers (km3) of volcanic materials into the atmosphere. This is enough to decrease global temperature by about 0.4 degrees Celsius for a few months. And about 70,000 years ago, at the site of today’s Lake Toba in Sumatra Indonesia, a supervolcano erupted releasing 2,800 km3 of volcanic materials into the atmosphere. This was enough to block out the sun for six to eight years, ushering in a period of global cooling that lasted for thousands of years.
Dr. Jean-Philippe Perrillat of the NCSR said that the difference in density between the molten magma and the rock surrounding it is enough to push the molten magma from the chamber into the surface violently. “The effect is like the extra buoyancy of a football when it is filled with air underwater, which forces it to the surface because of the denser water around it.” he added. This huge and violent explosion can happen especially if the volume of magma is already large enough as contained in the chamber and which can then penetrate the Earth’s crust.
The results of this study, published in the scientific journal Nature Geoscience was made possible through the use of a powerful X-ray machine located at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The X-ray machine took accurate density measurements at 36,000 times more than the normal atmospheric pressures and at temperatures reaching 1,700C. The study revealed that the density of the magma significantly decreased at that high pressure and temperature. According to the lead author of the study, Wim Malfait of ETH Zurich, a supervolcano can erupt primarily because of its enormous size and not because of any external factors like an earthquake.
To prevent the eruption of a supervolcano is beyond any human power to do. What humans can do is try to devise improved monitoring mechanisms and predict eruptions so that people may be warned ahead of time, added the scientists. Volcanic eruptions at the scale created by a supervolcano rarely occurs like once in every 100,000 years. Yet, when it occurs it can have a devastating impact on the Earth’s climate and the creatures living within it including humans.
There are six known supervolcanoes in the world right now and which include: the Yellowstone National Park in the U.S.; the Long Valley Caldera in east-central California; the Valles Caldera in northern New Mexico; Lake Toba in North Sumatra, Indonesia; the Taupo Caldera in New Zealand; and Aira Caldera in south Japan. The Yellowstone National Park sits on a vast molten rock and gasses and is considered as the largest active volcano in the world. Its last eruption was 600,000 years ago and released more than 1,000 km3 of ash and lava into the air which by estimates is enough to bury a city to a depth of a few kilometers.
A supervolcano eruption although rare can dramatically alter life on earth and can contribute to species’ mass extinction if ever it occurs. What is certain is that humans can never prevent it from happening. The least that humans can do is to prepare for its coming.
By Roberto I. Belda