Fault reactivation and active tectonics in NE Japan
Ching-Chia Huang
Abstract
In order to investigate the reverse reactivation tectonics in NE Japan, I choose three articles that talk about that. Northern Honshu is a classic example of trench-arc-back-arc system, Pacific plate subducted under the Eurasian plate beneath this area. This area have experienced three main geological events: extensional deformation since early Miocene, relative tectonic quiesce in late Miocene, and shortening deformation since late Pliocene.
The three researches study the area mainly by seismic reflection, and additional previous earthquake focal mechanism, aftershock distribution, surface and subsurface data, gravity data¡Ketc. By seismic profile, we can realize that the sediments on the hanging wall of the source reverse fault is thicker than that on the footwall, we also can see the Miocene half-graben structure in the seismic profile. Judging from these events, we can know the reverse reactivation of the Miocene basin-bounding normal fault, the active tectonics, and the pattern of the mid-crust detachment, then, reconstructed the balance geological cross section. Under the assumption of mid-crust detachment and listric geometry, the total quantity of compression of late Neogene was approximate 20% of the quantity of Miocene extension. Additionally, we can appreciate that reverse reactivation of pre-existing normal faults seems to occur where the precursor fault surfaces dip 60 degrees or less.
Reference
(1). Naoko Kato, Hiroshi Sato, Norihito Umino. Fault reactivation and active tectonics on the fore-arc side of the back-arc rift system,NE Japan. Journal of structural Geology 28 (2006)
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(2). Hiroshi Sato, Toshifumi Imaizumi, Takeyoshi Yoshida, Hisao Ito, Akira Hasegawa. Tectonic evolution and deep to shallow geometry of Nagamachi-Rifu Active Fault System, NE Japan. Earth Planets Space, 54, 2002.
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(3). Hiroshi Sato, Naoshi Hirata, Takaya Iwasaki, Makoto Matsubara, Takeshi Ikawa. Deep seismic reflection profiling across the Ou Backbone range, northern Houshu Island, Japan. Tectonophysics, 355, 2002.
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