Researchers: E. Brothelande, F. Amelung, and Z. Yunjun, University of Miami; S. Wdowinski, Florida International University.
Written by Linda Rowan
6 December 2019
GPS time series and deformation modeling show that the Aira and Kirishima volcanoes are connected at depth. When Kirishima erupted and extruded a large volume of lava, the geodetic data showed Kirishima rising and Aira falling. Modeling shows that a long graben provides a structure conducive for a magma reservoir extending beneath and between Aira and Kirishima. Geodetic observations can be used to determine the structure of volcanoes below the surface and help with hazard preparedness and response.
In southern Japan, a line of volcanoes has formed due to the subduction of the Phillipine Sea plate beneath the Eurasian plate. This line of volcanoes lies within a graben, an elongate structure between two faults with the center displaced downward. Two nearby volcanoes in this line are Aira and Kirishima. The volcanoes are about 22 kilometers apart and they are monitored for activity with GPS monuments and other surface instruments. Aira has been inflating and the GPS monuments showed vertical uplift for many decades before the 2011 eruption. In 2011, Kirishima erupted and extruded a large volume of lava. Here the authors compare geodetic measurements at the two volcanoes before, during and after the eruption and fit the data using a model of the dynamic connection between the volcanoes below the surface.
Multiple baselines between GPS monuments on the two volcanoes show how the volcanoes rise, fall and move horizontally before, during and after the 2011 eruption of Kirishima. Aira falls or deflates as Kirishima erupts and extrudes a large volume of lava onto the surface. Modeling shows that Aira is connected to Kirishima at depth by a large magma reservoir and the reservoir can exists partly because the volcanoes lie in a graben. The geodetic measurements clearly show the dynamic subsurface structure beneath the volcanoes and should help enhance our understanding of volcanic processes and improve hazard preparedness and response.
Brothelande, E., Amelung, F., Yunjun, Z. et al. Geodetic evidence for interconnectivity between Aira and Kirishima magmatic systems, Japan. Sci Rep 8, 9811 (2018) doi: 10.1038/s41598-018-28026-4 .
volcanic eruption, inflation, deflation, graben, subduction
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Last modified: 2020-01-28 22:16:23 America/Denver