scholarly journals Detailed tectonic geomorphology of the Dras fault zone, NW Himalaya

2021 ◽  
Vol 7 (3) ◽  
pp. 390-414
Author(s):  
AA Shah ◽  
◽  
A Rajasekharan ◽  
N Batmanathan ◽  
Zainul Farhan ◽  
...  
Keyword(s):  
Fault Zone ◽  
Normal Fault ◽  
Strike Slip ◽  
Tectonic Geomorphology ◽  
Earthquake Hazards ◽  
Active Faulting ◽  
Nw Himalaya ◽  
Border Regions ◽  
Major Fault ◽  
Fault Scarps

<abstract> <p>Our recent mapping of the Dras fault zone in the NW Himalaya has answered one of the most anticipated searches in recent times where strike-slip faulting was expected from the geodetic studies. Therefore, the discovery of the fault is a leap towards the understanding of the causes of active faulting in the region, and how the plate tectonic convergence between India and Eurasia is compensated in the interior portions of the Himalayan collision zone, and what does that imply about the overall convergence budget and the associated earthquake hazards. The present work is an extended version of our previous studies on the mapping of the Dras fault zone, and we show details that were either not available or briefly touched. We have used the 30 m shuttle radar topography to map the tectonic geomorphological features that includes the fault scarps, deflected drainage, triangular facets, ridge crests, faulted Quaternary landforms and so on. The results show that oblique strike-slip faulting is active in the suture zone, which suggests that the active crustal deformation is actively compensated in the interior portions of the orogen, and it is not just restricted to the frontal portions. The Dras fault is a major fault that we have interpreted either as a south dipping oblique backthrust or an oblique north dipping normal fault. The fieldwork was conducted in Leh, but it did not reveal any evidence for active faulting, and the fieldwork in the Dras region was not possible because of the politically sensitive nature of border regions where fieldwork is always an uphill task.</p> </abstract>

scholarly journals Seismic Activity of the Manisa Fault Zone in Western Turkey Constrained by Cosmogenic 36Cl Dating

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 451
Author(s):  
Nasim Mozafari ◽  
Çağlar Özkaymak ◽  
Dmitry Tikhomirov ◽  
Susan Ivy-Ochs ◽  
Vasily Alfimov ◽  
...  
Keyword(s):  
Fault Zone ◽  
Normal Fault ◽  
Vertical Displacement ◽  
Historical Records ◽  
Western Turkey ◽  
Slip Rates ◽  
Vertical Displacements ◽  
Surface Ruptures ◽  
Fault Scarps ◽  
Calculated Average

This study reports on the cosmogenic 36Cl dating of two normal fault scarps in western Turkey, that of the Manastır and Mugırtepe faults, beyond existing historical records. These faults are elements of the western Manisa Fault Zone (MFZ) in the seismically active Gediz Graben. Our modeling revealed that the Manastır fault underwent at least two surface ruptures at 3.5 ± 0.9 ka and 2.0 ± 0.5 ka, with vertical displacements of 3.3 ± 0.5 m and 3.6 ± 0.5 m, respectively. An event at 6.5 ± 1.6 ka with a vertical displacement of 2.7 ± 0.4 m was reconstructed on the Mugırtepe fault. We attribute these earthquakes to the recurring MFZ ruptures, when also the investigated faults slipped. We calculated average slip rates of 1.9 and 0.3 mm yr−1 for the Manastır and Mugırtepe faults, respectively.

scholarly journals Numerical modelling technique for predicting the seismic fault zone (SFZ) in the earthquakes affected area, NW Himalayas with its neotectonic implication

1970 ◽  
Vol 2 (2) ◽  
pp. 57-65
Author(s):  
M Farhad Howladar ◽  
Sharmin Afroz ◽  
Shofiqul Islam
Keyword(s):  
Fault Zone ◽  
Numerical Technique ◽  
Strain Analysis ◽  
Normal Fault ◽  
Focal Mechanism Solution ◽  
Mathematical Form ◽  
Finite Elements Analysis ◽  
Nw Himalaya ◽  
Potential Region ◽  
Seismic Fault

Finite elements analysis is a powerful tool, often used for analyzing problems on stress, that can be successfully employed to analyze the finite deformation of geological structures in a mathematical form on a digital computer. Over the last century, great earthquakes with magnitudes of 7->8 have struck in the NW Himalaya; the 1905 Kangra earthquake is one of them. This study performed a plane strain analysis of failure stress and faults in these earthquakes potential region based on the seismic geologic cross profile employing the two-dimensional finite element method under elastic material state with Mohr Coulomb failure criterion. The results show that the normal fault initiates at deeper level, whereas with increasing convergent displacement the thrust fault appears in the shallower region. The results of the simulation are compared with the available seismic and earthquakes focal mechanism solution data of the area which shows the close similarities between the distribution of simulated fault and microseismicity in the deeper region of Chamba Nappe (CN) and along the upper part of the Mid Crustal Ramp (MCR) which might be the Seismic Fault Zone (SFZ) of the region. Moreover, the intense localization of faults along the frontal part of the model indicates that this part is active in nature at present, which is responsible for the neotectonics in the Himalayas. Keywords: NW Himalaya; numerical technique; seismic fault zone; neotectonics DOI: 10.3329/jles.v2i2.7499 J. Life Earth Sci., Vol. 2(2) 57-65, 2007  

scholarly journals Active Faulting and Deformation of Quaternary Landform Sub-Himalaya, India

2010 ◽  
Vol 37 (-1) ◽  
pp. 63-71 ◽  
Author(s):  
Girish Kothyari ◽  
P. Pant ◽  
Moulishree Joshi ◽  
Khayingshing Luirei ◽  
Javed Malik
Keyword(s):  
Field Work ◽  
Tectonic Activity ◽  
Tectonic Geomorphology ◽  
Active Faulting ◽  
Main Boundary Thrust ◽  
Splay Faults ◽  
Fault Scarps

Active Faulting and Deformation of Quaternary Landform Sub-Himalaya, IndiaLandforms developed across terrain defining boundary the Main Boundary Thrust (MBT) have imprints of recent tectonic activity. Depositional landforms such as colluvial fan bear signatures of later phases of tectonic activity in the form of faulting of colluvial fan deposits and development of fault scarps. Tectonic geomorphology applied to the MBT zone suggests recent subsurface activity along the MBT and its splay thrusts. Present day tectonic activity of MBT is indicated by ground creeping, thrusting of Lower Siwalik rocks over recent colluvial fan deposit, aligning of series of lakes along splay faults and laterally along a fault, deflected streams, fault scarps and waterfalls. In the present paper we are addressing the tectonic situation in the foothill region of southeastern Kumaun Sub-Himalaya, India based on detailed field work carried out in the region which brought forward some outstanding morphotectonic evidence of neotectonic activities in the MBT zone.

Seismicity of Northern Anatolia

1976 ◽  
Vol 66 (3) ◽  
pp. 843-868
Author(s):  
James W. Dewey
Keyword(s):  
Fault Zone ◽  
Normal Fault ◽  
Large Earthquake ◽  
Field Studies ◽  
North Anatolian Fault ◽  
Time Intervals ◽  
Western Turkey ◽  
The North ◽  
Level Of Activity ◽  
Fault Scarps

abstract Earthquakes of magnitude 5.0 and greater that occurred in 1930-1972 in northern Anatolia have been relocated in order to define more accurately the characteristics of recent seismicity. The revised epicenters were determined either by joint epicenter determination (JED) or singly, with travel-times modified by JED-calculated source-station adjustments. Calibration epicenters were assigned on the basis of published field studies of the earthquakes. Many characteristics of the occurrence of magnitude 5.0 and greater earthquakes on the North Anatolian fault are similar to characteristics of small-earthquake seismicity on California's San Andreas fault. Earthquakes tend to be concentrated on or near particular sections of the North Anatolian fault, suggesting intrinsic differences in mechanical properties along the fault. The relocated epicenters support the hypothesis that fault rupture in large and great earthquakes will begin in regions of small and moderate earthquakes; the rupture of the large earthquake then propagates into sections of the fault that normally have a low level of activity. From 1939 through 1967, seven earthquakes of magnitude 6.8 or greater ruptured the North Anatolian fault from east to west for a distance of 800 km. Several sections of the fault zone were active before the occurrence of the large earthquakes of 1939-1967. Foreshock activity also extended tens of kilometers away from the fault zone. The time intervals between successive magnitude 6.0 or greater earthquakes on the fault are not consistent with a constant velocity of source migration; a model is proposed here in which these time intervals are equal to the duration of nonelastic effects precursory to the earthquakes. In western Turkey, the burst of normal-fault earthquakes in 1969-1970 was concentrated in distinctly separated source areas. The distribution of aftershocks to the earthquake of March 28, 1970 suggests that the surface fault scarps accompanying this earthquake are a distorted representation of the normal fault plane at depth.

scholarly journals Earthquake Hazards of the Grand Teton National Park Emphasizing the Teton Fault

1987 ◽  
Vol 11 ◽  
pp. 106-130
Author(s):  
D. Susong ◽  
R. Smith ◽  
R. Bruhn
Keyword(s):  
Fault Zone ◽  
Gravity Data ◽  
Hanging Wall ◽  
Regional Scale ◽  
Normal Fault ◽  
Earthquake Hazards ◽  
Eastern Front ◽  
The North ◽  
Teton Range ◽  
Structural Boundary

The Teton normal-fault zone extends for over 80 km along the eastern front of the Teton Range. Mapping and profiling of Quaternary fault scarps shows that the scarps are nearly continous for 55 km with scarp heights varying from about 10 m to 40 m. The largest scarps occur adjacent to the topographically highest parts of the Teton range. The scarps locally offset glacial moraine crests in a left-lateral sense. On a regional scale the scarps exhibit a right-stepping, en echelon geometry that is also consistent with a component of left-lateral displacenent. The Teton fault is structurally subdivided into three segments. One prominent geometrical segment boundary occurs just south Taggart Lake, where the range front bends through an angle of 23° and a major structural boundary extends through the hanging wall basin, as inferred by gravity data. This boundary may have influenced the history of Quaternary earthquake occurrences because vertical offset across faults scarps is greater to the north of the boundary, than to the south. The lengths of the proposed segments and scarp size are consistent with M7 to 7.5 earthquakes for the Teton fault zone.

scholarly journals 1993 Reobservations of the Teton Leveling Line for the Assessment of Earthquake Hazards

1993 ◽  
Vol 17 ◽  
pp. 103-105
Author(s):  
Arthur Sylvester ◽  
Robert Smith ◽  
David Morey
Keyword(s):  
Late Quaternary ◽  
Normal Fault ◽  
Earthquake Hazard ◽  
Level Line ◽  
Earthquake Hazards ◽  
Seismic Belt ◽  
Tectonically Active ◽  
Fault Scarps ◽  
Large Earthquakes

The Teton normal fault, Wyoming, is characterized by a 55-km long fault scarps of postglacial age (< 14,000 yrs.). These well developed late Quaternary scarps range in height from 3 to 52 m (Smith et al., 1993; Byrd et al., 1994) and have been the locus of several large, scarpforming earthquakes. The Teton fault is located in a tectonically active area of the Intermountain Seismic Belt but occupies a notable gap in the seismicity and is considered a major earthquake hazard to the region. The Teton fault is, therefore, considered a location of future large earthquakes with accompanying strain accumulation that may be measured by accurate measurements of changes in ground height, which has been the objective of our 1993 and past Teton fault leveling surveys. A 1st-class, 1st-order level line was established across the Teton fault in Grand Teton National Park in 1988 and has been observed in 1989, 1991, and 1993 to assess long-term deformation. This document is a progress report of the . most recent re-observations of the level line conducted in August, 1993.

scholarly journals Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Activity ◽  
Volcanic Rocks ◽  
Active Tectonics ◽  
Normal Fault ◽  
Aegean Sea ◽  
Northern Margin ◽  
The North ◽  
Eastern Aegean ◽  
Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

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