Volcanic activity rising beneath Yellowstone National Park in the United States appears to be becoming more active.
A new study shows that the magma reservoir that fuels supervolcano eruptions is moving northeast of the Yellowstone caldera. The region could become a new center of future volcanic activity, according to a team led by US Geological Survey seismologist Ninfa Bennington.
“Based on the presence of rhyolite melt storage beneath the northeastern Yellowstone Caldera and the fact that this area is directly connected to lower crustal heat sources, we suggest that the center of future rhyolite volcanism may have shifted northeast of the Yellowstone Caldera.” they write on paper.
“In contrast, over the past 160,000 years, post-caldera rhyolitic volcanic activity has occurred in most of the Yellowstone calderas except this northeastern region.”
Yellowstone is one of the largest supervolcanoes in the world. It is a vast, complex and dynamic region of the earth’s crust that is incredibly beautiful and extremely dangerous.
Over the past 2 million years, Yellowstone has experienced three massive caldera-forming eruptions. These explosions create cauldron-like basins on the Earth’s surface when underground magma chambers empty and collapse into empty space. These huge explosions were interspersed with smaller explosions.
Yellowstone’s caldera-forming eruptions occur in reservoirs such as: rhyolite dissolution. It is a silica-rich magma. It is a volcanic magma, like granite, and is sticky, viscous, and slow-moving. Vast quantities are thought to be stored beneath the Yellowstone region.
Previous research The rhyolite reservoir is believed to have been supported by a deeper reservoir of basaltic magma, a molten material that contains much less silica than rhyolite but is rich in iron and magnesium. That too quite a bit less viscous It is denser than rhyolite, and the way it conducts electricity is also different from rhyolite.
This latter characteristic difference gave Bennington and her colleagues the tools they needed to probe the contents of the magma reservoir beneath the Yellowstone Plateau.
One way to monitor activity below the Earth’s surface is to measure surface changes in the Earth’s magnetic and electric fields. These are known as magnetotellurics and are particularly sensitive to the presence of subsurface melt.
Bennington and her colleagues conducted an extensive magnetoelastographic survey throughout the Yellowstone Caldera and used the resulting data to model the distribution of molten reservoirs hidden within it.
Their results revealed that there are at least seven distinct regions of high magma content, some of which is flowing into other regions as deep as 4 to 47 kilometers (2.5 to 30 miles) underground, up to the crust-mantle boundary. .
The most interesting melt reservoir was in the northeast. There are huge reservoirs of basaltic magma in the lower crustal columns and chambers of rhyolitic magma in the upper crust. This chamber of rhyolite magma is estimated to store approximately 388 to 489 cubic kilometers of melt. This is almost 10 times higher than the melt storage areas to the south, west, and north where previous eruptions occurred.
Researchers note that this amount is also similar to the amount of melt from previous eruptions that formed the caldera in Yellowstone.
Rhyolite caldera-forming explosions are interspersed with smaller basalt explosions within the caldera, the researchers note. But exactly how these kinds of explosions work is unclear. The team’s work suggests that the rhyolitic magma chamber must be completely cooled before basaltic magma enters.
Researchers say further analysis is needed to determine exactly when and how future eruptions will occur.
This study was published in: nature.
