**9. Seismic tomography and fault plane solutions**

The estimated velocity images and fault-plane solutions are shed new light in understanding the fluvial network and geomorphic development in the intraplate region of Western India [15]. The epicenters of the relocated earthquakes show that the majority of the events are confined along F1–F4 (**Figure 1B**) during the recorded period. It is also noticed that some of small to moderate events are located north of F4 and north of F1 (**Figure 1B**). Interestingly, epicenters of small to moderate earthquakes are associated with the offset zone of fluvial network. Theses fluvial network are plotted over seismic tomography images at 5.0 km, 10.0 km, 15.0 km, 20.0 km, 25.0 km, and 30.0 km depths to understand brittle - ductile dynamics (**Figure 7A**). Based on significant perturbations in Vp anomalies, several shallow and deep fault controlling surface fluvial network are identified. Conventionally the low velocity of Vp anomalies at shallower to deeper depths represents presence of fluid, unconsolidated rocks fault gauge, cracks and fractured basement [15, 51, 58, 59]. Based on surface fluvial offset and velocity perturbation in depth sections of tomography data, the slow velocity is interpreted as a subsurface fracture pattern or strong heterogeneities. The high velocity zones at deeper depth are associated with the surface offset of drainage network [15].

The depth slices of tomography images are critically examined to identify subsurface fault pattern (**Figure 7A**). Both combined seismological and geological results clearly show that the zone between Bharudia/NWF and IBF is controlled by eight (F1–F8) E-W oriented parallel faults. Seismic tomograms at depths 5–15 km shows NW-SE and NE-SE oriented transverse faults. The Fault F4 is a vertical fault, which is well defined by velocity perturbations sections down to the depth of 30 km depth. Faults F1, F2, F3, F5, and F6 are connected with the F4 at 25 km deeper level (**Figure 7A**, **B**). However, the fault F7 is connected with F5 at 15 km depth, whereas the F8 joints with F7 down to the depth of 10 km. **Figure 7B** represents inferred depth geometric relationship of all these faults. Geometrically all these faults are converge at depth along a single sub-vertical fault (F4), making an E-W oriented negative flower structure, where all branches of faults are interacting at different depth resulting rhomb shape graben structure (**Figure 7B**). From the experimental model of [60] it is clear that the strike–slip fault zone is generally composed of several branches that join together at depth into a single vertical plane. As a consequence, bulk displacement accommodated at depth on the basement fault is distributed towards the surface among several faults whose tectonic activity evolves through time. Some branches remain inactive during a certain period, and then they are reactivated later when their geometry becomes compatible again with the evolving strain field in the wrench zone [60]. The model shows that the local relief apparently has a clear influence on subsurface fault geometries (**Figure 7A**). In the regions of low topography or where strong river incision traverses the wrench zone, a narrow releasing bend generally develops when the fault trace is deviated towards topographic lows. In regions of higher relief, compression is often associated with shearing, and the fault zone appears much more deformed and segmented [60]. From the earthquake fault plane solution data, it is clear that all these faults are strike slip pattern in nature (**Figures 1B, 6** and **7A**). However, a few solutions show thrust motions may be due to local tectonic adjustment between segmented fault blocks.

**10. Combined interpretation and discussion**

Globally, the rift basins are controlled by extensional tectonic forces. Changes of stress regime may cause inversion of such system from normal strike slip and reverse Coward [61], Scisciani [62] or by development of new faults between the basement rocks and overlying sedimentary succession [62, 63]. The wrench zone of a strike slip fault system shows complex arrays of structures in brittle upper crust in which fault splays are oblique to the principal fault trend

*satellite data to generate N-S topographic profile and final map has been generated using Surfer-14 software.*

**Figure 7.** (A) Stack map shows horizontal depth slices of P-wave seismic structures [51] at 5, 10, 15, 20, 25, and 30 km. The topographic surface level is highlighted by digital elevation model of the area. The fault lines F1 to F10 are marked based on offset of river along the wave velocity transition phase and highlighted by black dotted lines. (B) Dimensional block model of northern Wagad areas shows development of negative flower structure at deeper level as inferred from seismic structures. The position of faults on the top surface is marked by stream offset pattern. The depth behavior of fault is shown by fault plane solutions of [12–15]. Locations on the surface are marked by black filled circles; solid fill triangles represent location of GPS stations. (C) Schematic block model of Wagad region based on geological and seismological data shows development of negative flower structure towards the northern part of the area. The streams crossing these faults show prominent offset on the surface. *The, horizontal depth slices in* **Figure 1A** *are generated using MATLAB R2010 software and depth wise stack map of horizontal slices has been generated using Surfer-14 software. The P wave velocity slice* (**B**) *has been generated in MATLAB R2010 and the final editing has been done in Surfer software. For generation of* **C** *we used CARTOSAT* 

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147

Evolution of Drainage in Response to Brittle - Ductile Dynamics and Surface Processes… http://dx.doi.org/10.5772/intechopen.73653 147

**Figure 7.** (A) Stack map shows horizontal depth slices of P-wave seismic structures [51] at 5, 10, 15, 20, 25, and 30 km. The topographic surface level is highlighted by digital elevation model of the area. The fault lines F1 to F10 are marked based on offset of river along the wave velocity transition phase and highlighted by black dotted lines. (B) Dimensional block model of northern Wagad areas shows development of negative flower structure at deeper level as inferred from seismic structures. The position of faults on the top surface is marked by stream offset pattern. The depth behavior of fault is shown by fault plane solutions of [12–15]. Locations on the surface are marked by black filled circles; solid fill triangles represent location of GPS stations. (C) Schematic block model of Wagad region based on geological and seismological data shows development of negative flower structure towards the northern part of the area. The streams crossing these faults show prominent offset on the surface. *The, horizontal depth slices in* **Figure 1A** *are generated using MATLAB R2010 software and depth wise stack map of horizontal slices has been generated using Surfer-14 software. The P wave velocity slice* (**B**) *has been generated in MATLAB R2010 and the final editing has been done in Surfer software. For generation of* **C** *we used CARTOSAT satellite data to generate N-S topographic profile and final map has been generated using Surfer-14 software.*

## **10. Combined interpretation and discussion**

**9. Seismic tomography and fault plane solutions**

146 Tectonics - Problems of Regional Settings

depth are associated with the surface offset of drainage network [15].

tectonic adjustment between segmented fault blocks.

The estimated velocity images and fault-plane solutions are shed new light in understanding the fluvial network and geomorphic development in the intraplate region of Western India [15]. The epicenters of the relocated earthquakes show that the majority of the events are confined along F1–F4 (**Figure 1B**) during the recorded period. It is also noticed that some of small to moderate events are located north of F4 and north of F1 (**Figure 1B**). Interestingly, epicenters of small to moderate earthquakes are associated with the offset zone of fluvial network. Theses fluvial network are plotted over seismic tomography images at 5.0 km, 10.0 km, 15.0 km, 20.0 km, 25.0 km, and 30.0 km depths to understand brittle - ductile dynamics (**Figure 7A**). Based on significant perturbations in Vp anomalies, several shallow and deep fault controlling surface fluvial network are identified. Conventionally the low velocity of Vp anomalies at shallower to deeper depths represents presence of fluid, unconsolidated rocks fault gauge, cracks and fractured basement [15, 51, 58, 59]. Based on surface fluvial offset and velocity perturbation in depth sections of tomography data, the slow velocity is interpreted as a subsurface fracture pattern or strong heterogeneities. The high velocity zones at deeper

The depth slices of tomography images are critically examined to identify subsurface fault pattern (**Figure 7A**). Both combined seismological and geological results clearly show that the zone between Bharudia/NWF and IBF is controlled by eight (F1–F8) E-W oriented parallel faults. Seismic tomograms at depths 5–15 km shows NW-SE and NE-SE oriented transverse faults. The Fault F4 is a vertical fault, which is well defined by velocity perturbations sections down to the depth of 30 km depth. Faults F1, F2, F3, F5, and F6 are connected with the F4 at 25 km deeper level (**Figure 7A**, **B**). However, the fault F7 is connected with F5 at 15 km depth, whereas the F8 joints with F7 down to the depth of 10 km. **Figure 7B** represents inferred depth geometric relationship of all these faults. Geometrically all these faults are converge at depth along a single sub-vertical fault (F4), making an E-W oriented negative flower structure, where all branches of faults are interacting at different depth resulting rhomb shape graben structure (**Figure 7B**). From the experimental model of [60] it is clear that the strike–slip fault zone is generally composed of several branches that join together at depth into a single vertical plane. As a consequence, bulk displacement accommodated at depth on the basement fault is distributed towards the surface among several faults whose tectonic activity evolves through time. Some branches remain inactive during a certain period, and then they are reactivated later when their geometry becomes compatible again with the evolving strain field in the wrench zone [60]. The model shows that the local relief apparently has a clear influence on subsurface fault geometries (**Figure 7A**). In the regions of low topography or where strong river incision traverses the wrench zone, a narrow releasing bend generally develops when the fault trace is deviated towards topographic lows. In regions of higher relief, compression is often associated with shearing, and the fault zone appears much more deformed and segmented [60]. From the earthquake fault plane solution data, it is clear that all these faults are strike slip pattern in nature (**Figures 1B, 6** and **7A**). However, a few solutions show thrust motions may be due to local

Globally, the rift basins are controlled by extensional tectonic forces. Changes of stress regime may cause inversion of such system from normal strike slip and reverse Coward [61], Scisciani [62] or by development of new faults between the basement rocks and overlying sedimentary succession [62, 63]. The wrench zone of a strike slip fault system shows complex arrays of structures in brittle upper crust in which fault splays are oblique to the principal fault trend and generate a wide deformation zone [60, 64, 65]. The depth section of such faults tend to be steep at deeper level and to splay upwards, forming characteristic flower structures; have reverse (positive flower) or normal (negative flower) components [66, 67]. In such tectonic environment the shape of fault pattern is influenced by degradation and aggradation surface processes [68]. Conventionally in a negative flower zone the faults splays become listric as a result of synchronous deformation and sedimentation [69]. However, in a positive flower setting, faults tend to become steeper towards the surface as a result of aggradation in the footwall and degradation in the hanging wall [70–75].

In-SAR measurements show current deformation rate as ~16 mm/y in the western part and 7–16 mm/y in the southern part of the GF zone [14, 23, 80]. Based on trench investigation [63] estimated uplift rate of 0.5 ± 0.05 mm/y, horizontal shortening rate of 1.1 ± 0.12 mm/y along SWF. However based of fluvial offset [25] estimated slip rate 2.2 mm/y along the SWF zone which is compatible with the slip rate 1.19 ± 0.13 mm/y observed by [63]. Based on strath terraces [23] estimated the uplift rates 0.3 to 1.1 mm/y along F4, during the last 9 ka. Further, based on fluvial offset, we estimated slip rates for faults (F2–F10) using the imperial relationship given by [45]. The estimated slip rate along F2 of about 3.4 mm/y, along F3 of about 1.1 mm/y, along F4 of about 1.4 mm/y. along F5 of about 0.9 mm/y, along F6 of about 0.71 mm/y, along F7 of about 0.84 mm/y, along F8 of about 0.67 mm/y, along F9 of about 1.4 mm/y, and along F10 of about 3.1 mm/y (**Table 2**). The observed slip rate of F2–F10 are well corroborated with

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the uplift rate 0.3 to1.1 mm/y during the last 9 ka as estimated from the OSL dates.

controlled by localized crustal deformation.

bricks

4 2000BC

7 1300BC

multiple cracks running E-W

**Table 3.** List of historic earthquakes occurred in Kachchh region of western India.

rates obtained from drainage analysis are well correlated with the published results of GPS from the WH (ISR technical report by [81]. Four sites located in the southern part of study area shows variations in localized deformation (**Figure 7B**). The site Ekal shows deformation rate 2.5 ± 0.12 mm/y, Suvai is deforming at the rate of 1.9 ± 0.03 mm/yr., Badargadh is deformation at the rate of 1.8 ± 0.13 mm/y, and the site located near Rapar shows deformation rate of 2.1 ± 0.11 mm/y [81]. To sites Deshalpar and Fatehgadh shows deformation rates of 1.0 ± 0.04 mm/y and 1.7 ± 0.04 mm/y (**Figure 7B**). However, a site located in the northern part of study area shows crustal deformation rate 3.8 ± 0.14 mm/y [81]. The estimated slip rates and GPS driven deformation rates together suggests that the landform development in the area is

The future earthquake along active faults can be evaluated from estimates of fault rupture parameter in turn, released to earthquake magnitude [55]. Active fault studies require an assessment of seismic hazard analysis for the future potential earthquakes [55]. More specifically to estimate the size of earthquake that might be generated by a particular fault may be correlated with rupture parameter such as length, strike and displacement [55, 82, 83]. Moreover, the timing of the past earthquake and size of magnitude can be estimated with the help of geomorphic and paleoseismic records [84, 85]. We used regression analysis proposed by Wells and Coppersmith [55] and by Johnston [56] and Johnston and Kanter [86] for intraplate region to estimate moment magnitude. The detail regression analysis is expressed

**S. No Year Remarks References**

1 2900BC Damage in Dholavira, dislocation of walls, subsidence of floors and crushed

3 2100BC Damage in Dholavira; tremendous damage to the gates of castle, tilting and

2 2700BC Damage in Dholavira, 4 m wide fissured wall, collapse of southern features and

arching of thick inner walls and collapse of outer walls at north gate

6 1900BC Abandonment of settlements [63]

The slip

149

[77]

[78]

[79]

A wide zone of fault rupture pattern is investigated in WH of Kachchh peninsula. The seismic structures, seismicity and fault plane solution investigation show that the GF (F4) is a nearly vertical fault (**Figure 7B**, **C**) having dominant strike-slip deformation [15, 18, 51]. Using double difference tomography, we identified several shallower and deeper faults (F1–10); these faults are well connected with sub-vertical south dipping GF (F4) at different level (**Figure 7B** and **C**). Geometrical relationship inferred from seismic structures show all these faults are converge at certain depth along GF and making E-W oriented negative flower structure. All fault branches are interacting at different depth level and generating rhomb shape graben structure, which is well imaged in the seismic structures (**Figure 7B** and **C**). Depth section of tomography suggested that the faults F1, F2, F3, F5 and F8 are deeper faults. However, the F6 and F7 are imaged at shallower depth. It is also clear from the seismic structures that the fault F1 is a north dipping fault plane and connected with the F4 at 27 km depth level. The north dipping faults F2 and F3 and the south dipping faults F5 and F8 are connected with F4 at 25 km depth level. On the other hand the fault F6 is a southward dipping splay of F5 and connected with F5 at 15 km depth. The F7 is a small south dipping subsidiary branch of F6. The fault is connected with F6 at 12 km depth.

Conventionally, an extensional overstep zone of a strike–slip fault several branches that join together at depth into a single vertical plane [18]. As a consequence, bulk displacement accommodated at depth on the basement fault is distributed towards the surface among several faults whose tectonic activity evolves through time [60]. Some branches remain inactive during a certain period, and then they are reactivated later when their geometry becomes compatible again with the evolving strain field in the wrench zone [60]. A few researchers argued that KRB regions show dominantly strike-slip with the slightly reverse faulting natures [13, 51, 76]. However, a few solution shows reverse type of motion could be associated with the local tectonic adjustment between segmented fault blocks.

The archeological records from the WH experience several damaging earthquakes of magnitude 6.0–7.8; that have occurred between 2900 BC and 1300 BC (**Table 3**). The archeological evidences observed from 40 km west of study area (e.g. Dholavira) suggested that the ancient town was damaged by several major earthquakes between 2900BC and 1300BC [63, 77–79]. Presence of geomorphic and paleoseismic features within the WH, studied by previous workers are correlated with these historical earthquakes [23, 25, 63]. Further, based on trench investigation and optical chronology identified three earthquake events during last 7000 years [63]. The displaced fluvial sediment and optical chronology in the area suggested that the SWF reactivated during Middle to Late Holocene period i.e., between 3 ka and 1 ka [25]. Similarly other geomorphic studies suggest that the F4 reactivated during Middle Holocene around 4 ka [23].

In-SAR measurements show current deformation rate as ~16 mm/y in the western part and 7–16 mm/y in the southern part of the GF zone [14, 23, 80]. Based on trench investigation [63] estimated uplift rate of 0.5 ± 0.05 mm/y, horizontal shortening rate of 1.1 ± 0.12 mm/y along SWF. However based of fluvial offset [25] estimated slip rate 2.2 mm/y along the SWF zone which is compatible with the slip rate 1.19 ± 0.13 mm/y observed by [63]. Based on strath terraces [23] estimated the uplift rates 0.3 to 1.1 mm/y along F4, during the last 9 ka. Further, based on fluvial offset, we estimated slip rates for faults (F2–F10) using the imperial relationship given by [45]. The estimated slip rate along F2 of about 3.4 mm/y, along F3 of about 1.1 mm/y, along F4 of about 1.4 mm/y. along F5 of about 0.9 mm/y, along F6 of about 0.71 mm/y, along F7 of about 0.84 mm/y, along F8 of about 0.67 mm/y, along F9 of about 1.4 mm/y, and along F10 of about 3.1 mm/y (**Table 2**). The observed slip rate of F2–F10 are well corroborated with the uplift rate 0.3 to1.1 mm/y during the last 9 ka as estimated from the OSL dates. The slip rates obtained from drainage analysis are well correlated with the published results of GPS from the WH (ISR technical report by [81]. Four sites located in the southern part of study area shows variations in localized deformation (**Figure 7B**). The site Ekal shows deformation rate 2.5 ± 0.12 mm/y, Suvai is deforming at the rate of 1.9 ± 0.03 mm/yr., Badargadh is deformation at the rate of 1.8 ± 0.13 mm/y, and the site located near Rapar shows deformation rate of 2.1 ± 0.11 mm/y [81]. To sites Deshalpar and Fatehgadh shows deformation rates of 1.0 ± 0.04 mm/y and 1.7 ± 0.04 mm/y (**Figure 7B**). However, a site located in the northern part of study area shows crustal deformation rate 3.8 ± 0.14 mm/y [81]. The estimated slip rates and GPS driven deformation rates together suggests that the landform development in the area is controlled by localized crustal deformation.

and generate a wide deformation zone [60, 64, 65]. The depth section of such faults tend to be steep at deeper level and to splay upwards, forming characteristic flower structures; have reverse (positive flower) or normal (negative flower) components [66, 67]. In such tectonic environment the shape of fault pattern is influenced by degradation and aggradation surface processes [68]. Conventionally in a negative flower zone the faults splays become listric as a result of synchronous deformation and sedimentation [69]. However, in a positive flower setting, faults tend to become steeper towards the surface as a result of aggradation in the

A wide zone of fault rupture pattern is investigated in WH of Kachchh peninsula. The seismic structures, seismicity and fault plane solution investigation show that the GF (F4) is a nearly vertical fault (**Figure 7B**, **C**) having dominant strike-slip deformation [15, 18, 51]. Using double difference tomography, we identified several shallower and deeper faults (F1–10); these faults are well connected with sub-vertical south dipping GF (F4) at different level (**Figure 7B** and **C**). Geometrical relationship inferred from seismic structures show all these faults are converge at certain depth along GF and making E-W oriented negative flower structure. All fault branches are interacting at different depth level and generating rhomb shape graben structure, which is well imaged in the seismic structures (**Figure 7B** and **C**). Depth section of tomography suggested that the faults F1, F2, F3, F5 and F8 are deeper faults. However, the F6 and F7 are imaged at shallower depth. It is also clear from the seismic structures that the fault F1 is a north dipping fault plane and connected with the F4 at 27 km depth level. The north dipping faults F2 and F3 and the south dipping faults F5 and F8 are connected with F4 at 25 km depth level. On the other hand the fault F6 is a southward dipping splay of F5 and connected with F5 at 15 km depth. The F7 is a small south

dipping subsidiary branch of F6. The fault is connected with F6 at 12 km depth.

local tectonic adjustment between segmented fault blocks.

vated during Middle Holocene around 4 ka [23].

Conventionally, an extensional overstep zone of a strike–slip fault several branches that join together at depth into a single vertical plane [18]. As a consequence, bulk displacement accommodated at depth on the basement fault is distributed towards the surface among several faults whose tectonic activity evolves through time [60]. Some branches remain inactive during a certain period, and then they are reactivated later when their geometry becomes compatible again with the evolving strain field in the wrench zone [60]. A few researchers argued that KRB regions show dominantly strike-slip with the slightly reverse faulting natures [13, 51, 76]. However, a few solution shows reverse type of motion could be associated with the

The archeological records from the WH experience several damaging earthquakes of magnitude 6.0–7.8; that have occurred between 2900 BC and 1300 BC (**Table 3**). The archeological evidences observed from 40 km west of study area (e.g. Dholavira) suggested that the ancient town was damaged by several major earthquakes between 2900BC and 1300BC [63, 77–79]. Presence of geomorphic and paleoseismic features within the WH, studied by previous workers are correlated with these historical earthquakes [23, 25, 63]. Further, based on trench investigation and optical chronology identified three earthquake events during last 7000 years [63]. The displaced fluvial sediment and optical chronology in the area suggested that the SWF reactivated during Middle to Late Holocene period i.e., between 3 ka and 1 ka [25]. Similarly other geomorphic studies suggest that the F4 reacti-

footwall and degradation in the hanging wall [70–75].

148 Tectonics - Problems of Regional Settings

The future earthquake along active faults can be evaluated from estimates of fault rupture parameter in turn, released to earthquake magnitude [55]. Active fault studies require an assessment of seismic hazard analysis for the future potential earthquakes [55]. More specifically to estimate the size of earthquake that might be generated by a particular fault may be correlated with rupture parameter such as length, strike and displacement [55, 82, 83]. Moreover, the timing of the past earthquake and size of magnitude can be estimated with the help of geomorphic and paleoseismic records [84, 85]. We used regression analysis proposed by Wells and Coppersmith [55] and by Johnston [56] and Johnston and Kanter [86] for intraplate region to estimate moment magnitude. The detail regression analysis is expressed


**Table 3.** List of historic earthquakes occurred in Kachchh region of western India.

in **Table 2**. The regression analysis proposed by Wells and Coppersmith [55] and Johnston [56] shows strong correlation between surface rupture length and magnitude of earthquakes. However the regression analysis shows that probability of occurrence of earthquake magnitude range between 6.3 and 7.3) along F1, magnitude (M 5.4–M 7.3) along F2, magnitude (M 6.1–M 7.3) along F3, magnitude (M 6.7–M 7.3) along F4, magnitude (M 6.0–M 6.6) along F5, magnitude (M 6.7–M 7.3) along F6, magnitude (M 6.7–M 7.2) along F7, magnitude (M 6.2–M 7.2) along F8, magnitude (M 5.6- M 6.7) along F9, magnitude (M 5.6–M 7.0) along F10 respectively (**Table 2**). From the regression analysis it is clear that the faults (F1–F10) passes through the WH are capable for generating earthquake magnitude M 5.4 and M 7.3. Occurrence of February 2006M-5.6 along F9 validates our results and significant level.

evolution of the drainage basin which is influence by deep tectonic processes. Based on

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151

**1.** Based on analysis of fluvial offset and subsurface velocity images major 10 traces of active

**2.** The surface geomorphology, velocity imaging and fault plane solution data together sug-

**3.** The fault geometry inferred from seismic images show presence of negative flower struc-

**4.** The depth wise images show that the GF (F4) is steeply dipping towards south. The fault F1, F2 and F3 are dipping towards north, whereas, the fault F5–F8 are dipping towards south. All these faults are connected with GF (F4) at different depth level, which is well

The authors are thankful to Ministry of Earth Science, Government of India (MoES/ P.O.(Seismo)/1(270)/AFM/2015) for financial support under the active fault mapping program. We are thankful to Dr. M. Ravikumar, Director General and Dr. Sumer Chopra, Director,

Girish Ch Kothyari\*, Ajay P. Singh, Sneha Mishra, Raj Sunil Kandregula, Indu Chaudhary

gest that the subsurface structure of WH is controlled by strike slip faulting.

present observations the following conclusions have been drawn.

ture at a deeper level.

**Acknowledgements**

**Conflict of interest**

**Author's contribution**

**Author details**

and Gaurav Chauhan

imaged in the seismic structures.

fault (F1–F10) controlling hydraulic network have been identified.

Institute of Seismological Research, Gandhinagar for fruitful discussion.

There is no conflict of interest between all co-authors.

All the authors have made equal contribution in this manuscript.

\*Address all correspondence to: kothyarigirish\_k@rediffmail.com Institute of Seismological Research, Gandhinagar, Gujarat, India

Geomorphic indices are widely used to obtain index of active tectonics [25, 48–50]. Here we synthesized conventional geomorphic indices of active tectonics to calculate relative index of active tectonic (RIAT) distribution along the all fault segments (F1–F10). The RIAT classes show that the deformation is higher along the offset zone of fault segment (**Figure 5B**). Conventionally the SL and KS values show abnormal increase of gradient within normal and reverse faults. Minor changes of SL and KS observed within the zone of strike slip fault. At few places the SL and KS values do not shows any variation, which is compared with the strike slip motion of fault. The strike slip motion is well corroborated with the results of seismic tomography and fault plane solution (**Figure 7B**). The existing studies suggest that the terrain close to the GF (F4) experienced occurrence of moderate earthquakes during recent time [23, 27]. The strike slip motion observed from focal mechanism is well correlated with drainage offset along E-W oriented faults within the north and south flowing river system.

Further the observations gathered from the SL, KS and RIAT distribution are corroborated with the geomorphological studies carried out by [23]. The geomorphic expressions such as active fault scarp, shifting and offset of channels indicates that the area is controlled by E-W oriented strike slip faults. Further, steepening of river gradient as observed from tectonic proxy (SL and KS) and uplift of ground further support that the area is tectonically active. Previous studies by [23] suggests that the uplifts in GF zone were associated with interlinking of strike slip fault segments. Further major two phase of tectonic uplift have been identified by [23] based on uplifted fluvial strath terraces. The study shows that the first phase of enhanced uplift took place round 8.0 ± 0.9 ka; however, the second phase of uplift is began after 4 ka and continued till today [23]. In present study, several E-W oriented knickpoints were identified across north and south flowing drainage basins of WH. At several locations these knick points have migrated primarily due to river response to sudden base level fall and secondly incision owing to vertical tectonic forces. As sudden base-level fall can be triggered by tectonic upheaval, climatic change, river capture, or channel incision [87–89]. The incision by river and the formation of knickpoints are well correlated with tectonic upheaval along F1–F8 (**Figure 2A**).
