scholarly journals Correction to: Half-graben inversion tectonics revealed by gravity modeling in the Mikawa Bay region, Central Japan

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Ayumu Miyakawa ◽  
Tomoya Abe ◽  
Tatsuya Sumita ◽  
Makoto Otsubo
Keyword(s):  
Gravity Modeling ◽  
Inversion Tectonics ◽  
Central Japan ◽  
Half Graben

An amendment to this paper has been published and can be accessed via the original article.

scholarly journals Half-graben inversion tectonics revealed by gravity modeling in the Mikawa Bay Region, Central Japan

2020 ◽  
Author(s):  
Ayumu Miyakawa ◽  
Tomoya Abe ◽  
Tatsuya Sumita ◽  
Makoto Otsubo
Keyword(s):  
Gravity Data ◽  
Sedimentary Cover ◽  
Active Faults ◽  
Normal Fault ◽  
Gravity Modeling ◽  
Inversion Tectonics ◽  
Central Japan ◽  
Basin Inversion ◽  
Reverse Faulting ◽  
Half Graben

Abstract The Mikawa Bay Region, central Japan, is characterized by many active faults recording Quaternary activities. It is, however, difficult to understand the overall tectonic character of the region due to a thick sedimentary cover. We report the first finding of Neogene basin inversion in southwest Japan by estimating the depth and structure of the basement surface in the Mikawa Bay Region by analyzing gravity data. Our gravity basement map and two-dimensional density-structure model automatically determined using the genetic algorithm revealed a half-graben bounded on the south by the north-dipping Utsumi Fault. The motion of the Utsumi Fault, which inverted from normal faulting during the Miocene to recent reverse faulting, indicated the inversion of the half-graben. The timing of the inversion of the fault motion, i.e., the reverse faulting of the Miocene normal fault, can be compared with an episode of basin inversion observed at the eastern margin of the Japan Sea, northeastern Japan. The Takahama Fault in the southwestern part of the Nishi–Mikawa Plain is considered to have formed as a result of the backthrust of the Utsumi Fault under inversion tectonics. If the Takahama Fault is indeed the backthrust fault of the Utsumi Fault, the root of the Takahama Fault may be deep such that the Takahama Fault is seismogenic and linked to the 1945 Mikawa earthquake.

scholarly journals Half graben inversion tectonics revealed by gravity modeling in the Mikawa Bay Region, Central Japan

2020 ◽  
Author(s):  
Ayumu Miyakawa ◽  
Tomoya Abe ◽  
Tatsuya Sumita ◽  
Makoto Otsubo
Keyword(s):  
Gravity Data ◽  
Sedimentary Cover ◽  
Active Faults ◽  
Normal Fault ◽  
Gravity Modeling ◽  
Inversion Tectonics ◽  
Central Japan ◽  
Basin Inversion ◽  
Reverse Faulting ◽  
Half Graben

Abstract The Mikawa Bay Region, central Japan, is characterized by many active faults recording Quaternary activities. It is, however, difficult to understand the overall tectonic character of the region due to a thick sedimentary cover. We report the first finding of Neogene basin inversion in southwest Japan by estimating the depth and structure of the basement surface in the Mikawa Bay Region by analyzing gravity data. Our gravity basement map and two-dimensional density-structure modeling revealed a half graben bounded on the south by the north-dipping Utsumi Fault. The motion of the Utsumi Fault, which inverted from normal faulting during the Miocene to recent reverse faulting, indicated the inversion of the half graben. The timing of the inversion of the fault motion, i.e. the reverse faulting of the Miocene normal fault, can be compared with an episode of basin inversion observed at the eastern margin of the Japan Sea, northeastern Japan. The Takahama Fault in the southwestern part of the Nishi–Mikawa Plain is considered to have formed as a result of the backthrust of the Utsumi Fault under inversion tectonics. If the Takahama Fault is indeed the backthrust fault of the Utsumi Fault, the root of the Takahama Fault may be deep such that the Takahama Fault is seismogenic and linked to the 1945 Mikawa earthquake.

scholarly journals Half graben inversion tectonics revealed by gravity modeling in the Mikawa Bay Region, Central Japan

2020 ◽  
Author(s):  
Ayumu Miyakawa ◽  
Tomoya Abe ◽  
Tatsuya Sumita ◽  
Makoto Otsubo
Keyword(s):  
Gravity Data ◽  
Active Faults ◽  
Normal Fault ◽  
Japan Sea ◽  
Gravity Modeling ◽  
Inversion Tectonics ◽  
Central Japan ◽  
Basin Inversion ◽  
Reverse Faulting ◽  
Half Graben

Abstract The Mikawa Bay Region, central Japan, is characterized by many active faults recording Quaternary activity. It is, however, difficult to understand the overall tectonic character of the region due to the thick sediments in this region. We estimated the depth and the structure of the basement top in the Mikawa Bay Region through the analysis of gravity data, compiling publicly available gravity data and our own gravity measurements in the central part of the region. The gravity basement map shows the deepening of the basement top from the Nishi-Mikawa Plain to the Chita Peninsula. Two-dimensional modeling constrains the orientation of the Utsumi and Takahama faults. The fact that the basement top structure related to the Kou Fault is insignificant in the gravity data indicates that the geometry of the Kou Fault is small relative to that of the Utsumi Fault. The basement top structure from the Nishi-Mikawa Plain to the Chita Peninsula reveals a half graben structure bounded by the Utsumi Fault. The inverse motion of the Utsumi Fault, which underwent normal faulting during the Miocene followed by recent reverse faulting, is interpreted to reflect the inversion tectonics of the half graben. The timing of the inversion tectonics, i.e. the reverse faulting of the Miocene normal fault, can be compared to an episode of basin inversion observed at the eastern margin of the Japan Sea, northeastern Japan. The Takahama Fault in the center of the Nishi-Mikawa Plain is considered to have formed as a result of the backthrust of the Utsumi Fault under inversion tectonics. If the Takahama Fault is indeed the backthrust fault of the Utsumi Fault, the root of the Takahama Fault may be deep such that the Takahama Fault is seismogenic and linked to the 1945 Mikawa earthquake.

scholarly journals Half-graben inversion tectonics revealed by gravity modeling in the Mikawa Bay Region, Central Japan

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Ayumu Miyakawa ◽  
Tomoya Abe ◽  
Tatsuya Sumita ◽  
Makoto Otsubo
Keyword(s):  
Gravity Data ◽  
Sedimentary Cover ◽  
Active Faults ◽  
Normal Fault ◽  
Gravity Modeling ◽  
Inversion Tectonics ◽  
Central Japan ◽  
Basin Inversion ◽  
Reverse Faulting ◽  
Half Graben

AbstractThe Mikawa Bay Region, central Japan, is characterized by many active faults recording Quaternary activities. It is, however, difficult to understand the overall tectonic character of the region due to a thick sedimentary cover. We report the first finding of Neogene basin inversion in southwest Japan by estimating the depth and structure of the basement surface in the Mikawa Bay Region by analyzing gravity data. Our gravity basement map and two-dimensional density-structure model automatically determined using the genetic algorithm revealed a half-graben bounded on the south by the north-dipping Utsumi Fault. The motion of the Utsumi Fault, which inverted from normal faulting during the Miocene to recent reverse faulting, indicated the inversion of the half-graben. The timing of the inversion of the fault motion, i.e., the reverse faulting of the Miocene normal fault, can be compared with an episode of basin inversion observed at the eastern margin of the Japan Sea, northeastern Japan. The Takahama Fault in the southwestern part of the Nishi–Mikawa Plain is considered to have formed as a result of the backthrust of the Utsumi Fault under inversion tectonics. If the Takahama Fault is indeed the backthrust fault of the Utsumi Fault, the root of the Takahama Fault may be deep such that the Takahama Fault is seismogenic and linked to the 1945 Mikawa earthquake.

Conceptual model of basement deformation beneath the Southern Atlassic front of Tunisia from gravity modeling, seismic reflection profiles and seismotectonic data

2021 ◽  
Author(s):  
Nesrine Frifita ◽  
Mohamed Gharbi ◽  
Kevin Mickus
Keyword(s):  
Seismic Reflection ◽  
Geological Mapping ◽  
Gravity Modeling ◽  
Basement Faults ◽  
Geophysical Study ◽  
Half Graben ◽  
Basement Structures ◽  
Tectonic Style ◽  
Basement Deformation ◽  
Seismic Reflection Profiles

<p>The nature of the basement beneath the Southern Atlassic front of Tunisia is relatively unknown. To study the basement, a geophysical study was undertaken using gravity, seismic reflection and seismicity data. Additionally, these data were used to determine the relationship and the tectonic environment between the known seismicity and basement structures under the Chotts fold belt and the surrounding basins. Based on 2.5D gravity modeling, 2D seismic reflection profiles and known geological mapping, the geometry of the basement was modeled as consisting of horsts,grabens and half-grabens. Specifically, the Sidi Mansour and El-Fejej basins are located on basement uplifts. The variations in the depths of the known earthquakes reveal that the deepest events occurred on basement faults beneath the Metlaoui and Sidi Mansour basins. While the surrounding anticlines within the northern Chotts range are probably inverted into graben and half-graben structures by both thin- and thick-skinned tectonic events. The geophysical findings indicate that the geometry of the basement to consist of a series of uplifted and downdropped regions, where the depth to basement increases from south to north and from east to west. This basement structure can explain the concentration of earthquakes in the northwestern portion of the study area by linking a reactivation of pre-existing east trending fault systems that formed during Alpine Orogeny. The results provide a coherent model showed a mixed thick and thin-skinned tectonic style was active within the study area. </p>

scholarly journals The role of backstop shape during inversion tectonics physical models

2010 ◽  
Vol 82 (4) ◽  
pp. 997-1012 ◽  
Author(s):  
Caroline J.S. Gomes ◽  
André Danderfer Filho ◽  
Ana Maria A. Posada ◽  
Anielle C. da Silva
Keyword(s):  
Laboratory Experiments ◽  
Hanging Wall ◽  
Physical Models ◽  
Normal Faults ◽  
Crustal Extension ◽  
Inversion Tectonics ◽  
Physical Experiments ◽  
Half Graben

The style of deformation of rocks from basin-infilling sequences in positively inverted natural basins was discussed upon the results of laboratory experiments carried out in sandboxes with sand packs laid down in the space between two wooden blocks. The space simulated stages of crustal extension leading to (1) a half graben due to extension above a listric extensional detachment, with the blocks simulating the footwall and hanging wall, or (2) a graben, with the blocks simulating the external margins that drifted apart above a horizontal detachment. Combinations of two different angles were used to simulate the dip of curved normal faults along the internal face of the wooden blocks. Backstops in the half graben had a convex up internal face. Backstops in the graben had a concave up internal face. Shortening as partitioned in forward and backward movements within the sand packs, and the kinematics of contraction was largely influenced by the convex or concave internal faces. A buttress effect characterized by rotation of the sand pack close to the footwall was stronger for footwall with steeper-dipping internal faces. The results were compared to other physical experiments and applied to an inverted basin found in nature.

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