Study finds deep subterranean connection between two Japan volcanoes

Scientists use GPS data to uncover unusual behavior between distant
volcanoes

University of Miami Rosenstiel School of Marine & Atmospheric Science
IMAGE

IMAGE: Southern Japan on Feb. 3rd, 2011, showing the active cones of
Kirishima (Shinmoedake) and Aira caldera (Sakurajima) volcanoes. While Kirishima is erupting very strongly, Aira's activity is relatively
low.... view more

Credit: NASA

MIAMI--Scientists have confirmed for the first time that radical changes
of one volcano in southern Japan was the direct result of an erupting
volcano 22 kilometers (13.7 miles) away. The observations from the two volcanos--Aira caldera and Kirishima--show that the two were connected
through a common subterranean magma source in the months leading up to
the 2011 eruption of Kirishima.

The Japanese cities of Kirishima and Kagoshima lie directly on the
border of the Aira caldera, one of the most active, hazardous, and
closely monitored volcanoes in southern Japan. Identifying how volcanoes interact is critical to determine if and how an eruption can influence
the activity of a distant volcano or raise the threat of a new strong
explosive event.

The research team from the University of Miami's (UM) Rosenstiel School
of Marine and Atmospheric Science and Florida International University
analyzed deformation data from 32 permanent GPS stations in the region
to identify the existence of a common magma reservoir that connected the
two volcanoes.

Leading up to the eruption of Kirishima, which is located in the densely-populated Kagoshima region, the Aira caldera stopped inflating,
which experts took as a sign that the volcano was at rest. The results
from this new study, however, indicated that the opposite was
happening--the magma chamber inside Aira began to deflate temporarily
while Kirishima was erupting and resumed shortly after the activity at Kirishima stopped.

"We observed a radical change in the behavior of Aira before and after
the eruption of its neighbor Kirishima," said Elodie Brothelande, a postdoctoral researcher at the UM Rosenstiel School and lead author of
the study. "The only way to explain this interaction is the existence of
a connection between the two plumbing systems of the volcanoes at depth."

Prior to this new study, scientists had geological records of volcanoes erupting or collapsing at the same time, but this is the first example
of an unambiguous connection between volcanoes that allowed scientists
to study the underlying mechanisms involved. The findings confirm that volcanoes with no distinct connection at the surface can be part of a
giant magmatic system at depth.

"To what extend magmatic systems are connected is an important question
in terms of the hazards," said Falk Amelung, professor of geophysics at
the UM Rosenstiel School and coauthor of the study. "Is there a lot of
magma underground and can one eruption trigger another volcano? Up until
now there was little or no evidence of distinct connections."

"Eruption forecasting is crucial, especially in densely populated
volcanic areas," said Brothelande. "Now, we know that a change in
behavior can be the direct consequence of the activity of its neighbor Kirishima."

The findings also illustrate that large volcanic systems such as Aira
caldera can respond to smaller eruptions at nearby volcanoes if fed from
a common deep reservoir but not all the time, since magma pathways open
and close periodically.

"Now, we have to look whether this connnection is particular for these volcanoes in southeastern Japan or are widespread and occurr around the
world," said Amelung.

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The study, titled "Geodetic evidence for interconnectivity between Aira
and Kirishima magmatic systems, Japan," was published June 28 in the
journal Scientific Reports. The coauthors include: Elodie Brothelande,
Falk Amelung and Zhang Yunjun from the UM Rosenstiel School of Marine
and Atmosheric Science and Shimon Wdowinski of Florida International University. The study was supported by NASA's Earth Surface and Interior Program (grant #NNX16AL19G).

About the University of Miami's Rosenstiel School

The University of Miami is one of the largest private research
institutions in the southeastern United States. The University's mission
is to provide quality education, attract and retain outstanding
students, support the faculty and their research, and build an endowment
for University initiatives. Founded in the 1940's, the Rosenstiel School
of Marine & Atmospheric Science has grown into one of the world's
premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to
helping communities to better understand the planet, participating in
the establishment of environmental policies, and aiding in the
improvement of society and quality of life. For more information, visit: http://www.rsmas.miami.edu.

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