Northern Honshu, Japan, is a classic example of a trench-arc-back-arc system.
At present, northern Honshu undergoes contraction perpendicular to the
NNE-SSW-trending arc as indicated by geodetic measurements, active faults
(Active Fault Research Group, 1991) and focal mechanisms (e.g., Hasegawa
et al., 2000).
On the fore-arc side of northern Honshu, pre-Neogene rocks consist of a Jurassic accretionary complex locally intruded by Cretaceous granites and extensively crop out in the Kitakami massif. The family of lower Neogene, largely Miocene extensional structures that stretches for over 300 km along the western margin of the Kitakami massif is here defined as the Kitakami fault system.
The western margin of the Kitakami massif is marked by a steep Bouguer anomaly gradient, suggesting a subsided back-arc structure. The figure below shows the geological map of the Kitakami Lowland and the seismic reflection profile plotted together with the source location on the possible active fault called the Detana Fault. (We need more information to identify where the exact source location is.) We can see the reverse reactivation of pre-existing normal faults along the Kitakami fault system, i.e.; 1) syn-rift normal faulting, 2) post-rift rectonic quiescene, and 3) reverse normal fault reactivation during positive inversion.
[More details in Naoko Kato, Hiroshi Sato, and Norihito Umino,Fault reactivaion and active tectonics on the fore-arc side of the back-arc
rift system, NE Japan, Journal of Structural Geology, 28, 2011-2022, 2006]
References:
Susumu Abe, Hideo Saito, Hiroshi Sato, Shin Koshiya, Naoko Kato, Kazuya Shiraishi, Taku Kawanaka, Multidisciplinary Seismic Survey across the Kitakami Lowland, Northeast Japan.,Japan Geoscience Union Meeting 2008, 2008. Hideo Saito, Susumu Abe, Kazuya Shiraishi, Hiroshi Sato, Shin Koshiya, Naoko Kato, Taku Kawanaka, Deep Seismic Reflection Profiling across the Kitakami Lowland, Northeast Japan, Japan Geoscience Union Meeting 2008, 2008. Hideo Saito, Susumu Abe, Kazuya Shiraishi (JGI, Inc.), Hiroshi Sato (ERI, Univ. of Tokyo),Shin Koshiya (Iwate Univ.), Naoko Kato (ERI, Univ. of Tokyo), Taku Kawanaka (JGI, Inc.), Deep seismic reflection profiling across the Kitakami lowland, northeast Japan, SEGJ 118th (2008 Spring) Meeting, 2008. Susumu Abe, Hideo Saito(JGI, Inc.),Hiroshi Sato(ERI, Univ. of Tokyo),Shin Koshiya(Iwate Univ.),Kazuya Shiraishi, Fumitoshi Murakami(JGI, Inc.),Naoko Kato(ERI, Univ. of Tokyo),Taku Kawanaka, Toru Kuroda(JGI, Inc.), Integrated seismic imaging of active and passive data for the delineation of active faults and crustal structure in the Kitakami lowland, northeast Japan, SEGJ 118th (2008 Spring) Meeting, 2008. Hideo Saito, Susumu Abe, Hiroshi Sato, Shin Koshiya, Naoko Kato, Taku Kawanaka, Deep Seismic Reflection Profiling across the Kitakami Lowland, Northeast Japan, European Geosciences Union General Assembly, 2008.
(Written originally by Naoko Kato, translated into English by Satoko Oki)