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Hirahara, Kazuro*; Ozono, Mako*; Sagiya, Takeshi*; Hoso, Yoshinobu*; Wada, Yasuo*; Ando, Masataka*
Geodynamics of Atotsugawa Fault System, p.25 - 44, 2007/00
no abstracts in English
Kinoshita, Hirohisa; Nohara, Tsuyoshi; Nakata, Takashi*; Ikeda, Yasutaka*; Ito, Kiyoshi*; Otsuki, Kenshiro*; Sagiya, Takeshi*; Takada, Keita*; Toda, Shinji*
Katsudanso Kenkyu, (25), p.27 - 37, 2005/06
Results of numerical analyses and field studies in the epicenter area of the 2000 Tottoriken-seibu earthquake suggest that several research techniques are effective for identifying subsurface active faults unaccompanied with remarkable surface earthquake faults. Field observation of the lineaments found in the area by detailed air-photo interpretation revealed that most of them are accompanied by faults and/or dikes, and some of them show minor slips at the time of the earthquake. Crustal deformation caused by the activity of the subsurface seismogenic faults is deduced by numerical analyses based on seismic and geodetic data. The vertical deformation assumed from the height changes of the terraces along the river across the epicenter area suggests that cumulative uplift and subsidence associated with left-lateral strike-slip has been continuing. Offsets rate of the streams and uplift rate of the river terraces surfaces show good agreement with the estimate from the parameter of the earthquake faults model. Identification of active faults without clear surface evidence before occurrence of earthquakes is a difficult issue, and the techniques adopted in this study will probably provide relevant information effective to locate subsurface active faults.
Sagiya, Takeshi*
JNC TJ7400 2004-010, 37 Pages, 2004/02
JNC-TJ7400-2004-010.pdf:4.25MB
I examined new methodologies for investigating inland seismogenic faults with GPS data. Inland crustal deformation is sometimes significantly affected by plate coupling at subduction zones. Therefore it is quite important to remove such effects from original GPS data in order to discuss inland seismogenic faults. It is suggests that we need a simultaneous analysis of nationwide GPS data and introduction of physical constraint such that the coupling vectors are directed along the relative plate motion. On the other hand, I compared geologically estimated slip rates of active faults and geodetic data around those faults in order to chech consistency between these two data sets. Although these two data have significantly different strain rates, it is concluded that direct comparison of these two data sets is not reasonable and other aspects such as the displacement rate can be comprehensively understood. In addition, crustal deformation associated with active faults appears within a finite width, which is highly variable among active faults, around each active fault. Though these investigations, an applicability of GPS data for investigating inland seismogenic faults is confirmed.
Nohara, Tsuyoshi; Nakata, Takashi*; Sagiya, Takeshi*; Kinoshita, Hirohisa; Shimada, Koji
no journal, ,
Features of subsurface active faults are studied using data of the damaging earthquake, geological structure and diastrophism. It is considered that the scales of the subsurface active faults are not more than 6.6 (Mw). The hypocenter of the damaging earthquakes distribute around the Quaternary volcanoes and the active faults. The direction of strike and displacement of the active faults and the earthquake faults of the damaging earthquakes occurred around the active faults are almost same. The dispersion of the deformation of the mylonite zone related to geological condition may be one of the indicators of generation of subsurface active fault. GPS data analysis for the Atotsugawa fault can be confirmed the activity of this active fault zone. GPS data do not indicate the presence of many unknown subsurface active faults.
Nohara, Tsuyoshi; Nakata, Takashi*; Shimada, Koji; Niwa, Masakazu; Kinoshita, Hirohisa; Sagiya, Takeshi*
no journal, ,
Features of subsurface active faults are studied using data of the damaging earthquake, geological structure and diastrophism. The hypocenter of the damaging earthquakes distribute around the Quaternary volcanoes and the active faults. The direction of strike and displacement of the active faults and the earthquake faults of the damaging earthquakes occurred around the active faults are almost same. The dispersion of the deformation of the mylonite zone related to geological condition may be one of the indicators of generation of subsurface active fault.
