2000年有珠山噴火活動の時定数(<特集>2000年有珠山噴火 (3))

概要

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The temporal variation of the ground deformation in case of the 2000 eruption of Volcano Use has been detected by the GPS observation conducted by Geographical Survey Institute, Geological Survey of Hokkaido and Hokkaido University. The process is modeled considering a system composed of magma intrusion as a source and crustal structure as a complex medium applying the theory of the intercellular response of the nerve cell. The system response indicates the time evolution of apparent ground deformation started at about 9 o'clock in the morning of March 29, 2000 and lasted until the time of the eruption on March 31. The deformation continued as the relaxation process with a decay time constant of 1.2 to 1.5 days and never has been excited again. This gradual relaxation harmonizes with our repeated gravity measurement surrounding Volcano Usu. The deformation in the vicinity of the Nishiyama crater lasted more or less longer until April 2. After that, the relaxation of the deformation with a decay time constant of 3 to 3.5 days has been observed near the crater region, suggesting two different temporal variations of the deformation processes.
2002-11-29