an integrated geomorphological and geophysical study of

An integrated geomorphological and geophysical studyof neotectonic activity: Analysis of heavy siltationin the Chilka Lake of Odisha, India

SUBHAMOY JANA, WILLIAM KUMAR MOHANTY*, SAIBAL GUPTA

and PRAKASH KUMAR

Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721 302, India.*Corresponding author. e-mail: [email protected]

MS received 17 September 2020; revised 28 March 2021; accepted 29 May 2021

The present study investigates the reasons for the heavy siltation in Chilka Lake which is analysedby satellite imagery, ground survey and geophysical studies. ModiBed normalized difference water index(MNDWI) and linear spectral unmixing method (LSU) reveal the presence of a wetland, suspendedsediments and aquatic weeds along the northeastern boundary of the lake and beyond. Gravity, magneticdata and 3D inversion modelling reveal various sets of faults that were periodically reactivated to formuplifted and subsided blocks around the lake. Geomorphic evidence like low valley width/height ratio (Vf)with\1.5 (valley undercutting due to uplift), low mountain front sinuosity index (Smf ), basin asym-metry, transverse topographic symmetry (T ), compressed meanders, and Cow diversion are all indicativeof neotectonic activity and the resulting reactivation of faults. Neotectonic activity is also evidenced fromthe occurrence of seismic tremors in and around the Chilka region which lies in Zone III of the seismiczonation map of India. This neotectonic activity can be related to the compressional stresses persistingover most parts of the Indian Shield due to the Himalayan Orogeny. The resulting uplift and subsidenceled to erosion of the uplifted block and sedimentations in the subsided block by the rivers Daya andBhargabi. This is the probable cause of heavy siltation in Chilka Lake, where the eroded sediments of theuplifted block are deposited by these two rivers.

Keywords. Bhargabi; Chilka; Daya; Mahanadi; neotectonic; siltation.

1. Introduction

Neotectonic activity occurs in most parts of theIndian Shield to accommodate shortening causedby the Himalayan Orogeny. The accumulatedcompressional stresses are manifested as seismictremors of low to moderate seismic intensity invarious parts of India as well as the adjacent Bayof Bengal (Krishna et al. 2001, 2009; Anand andRajaram 2004; Ramasamy 2006; Kothyari andRastogi 2013; Rao et al. 2015; Bhattacharjee et al.

2016). Jade (2004) and Banerjee et al. (2008)reported the crustal shortening within the Indianshield based on a geodetic GPS survey. Theeastern coastal plain of Odisha, which lies in bothzones II and III of the seismic zonal map of India,also experiences tectonic activity as inferred fromgravity, magnetic and seismic data (Vaidyanad-han and Ghosh 1993; Dhar et al. 2017). Severalearthquakes of low to moderate magnitude havebeen reported from historical times to the presentin a few places of coastal Odisha (which lies both

J. Earth Syst. Sci. (2021) 130:220 � Indian Academy of Scienceshttps://doi.org/10.1007/s12040-021-01702-2 (0123456789().,-volV)(0123456789().,-volV)

in zones II and III of Seismic Zonation Map ofIndia, BIS 2002) as well as the adjoining Bay ofBengal; these are shown in Bgure 1 and table 1(http://asc-india.org/seismi/seis-orissa.htm). Someexamples of recent tectonic movements, like thedisplacement of the Quaternary sediments by aseries of faults and channel shifting, have beenreported earlier by Bharali et al. (1991) and

Vaidyanadhan and Ghosh (1993). In the Chilkaregion, evidence of mild tectonic activity in thepast was reported by Venkatarathnam (1970),who inferred this tectonic activity to have startedbefore 3750 ± 200 years BP based on the radio-carbon dating of fossil fauna. Mahalik (2006)reported the frequent occurrence of earthquakes inseveral regions of Odisha which include

Figure 1. (a) The map of Odisha shows the earthquake epicentres, the neo-tectonic faults and different seismic zones (modiBedafter Dhar et al. 2017). The details of most of the earthquake epicentres (date and place are taken from site http://asc-india.org/seismi/seis-orissa.htm) marked by serial number are given in table 1. (b) The different earthquake zones where earthquakesoccur frequently are shown in Odisha map (modiBed after Mahalik 2006).

220 of 20 J. Earth Syst. Sci. (2021) 130:220

Sambalpur–Jharsuguda–Sundargarh, Sambalpur–Talcher, Sundargarh–Rourkela, Talcher, Barkot–Rourkela and Berhampur–Jankia (Bgure 1b).Among these, the Berhampur–Jankia region in theproximity of the Chilka Lake (Bgure 1), is locatedat the junction between the Eastern Ghats horstand the coastal graben. Chilka, the largest brackishwater lake in Asia and the second largest in theworld, extends 64 km in the NE–SW and 5–18 kmin the S–N direction (Panigrahi et al. 2007). Thelake is bounded by several parallel spits in thesouth which separate it from the Bay of Bengal(Venkatarathnam 1970). At present, the lake,which has an area of about 1165–906 km2 duringmonsoon and summer, respectively, is shrinkingdue to land reclamation for agriculture, aquacul-ture and sediment inCow (Kumar et al. 2016). Thesediment inCow mainly comprises total suspendedsediments (TSS), nitrates and phosphates. Aquaticweeds, mainly phytoplanktons, are more commonin the northern, compared to the central orsouthern sides (Panigrahi et al. 2007).Earlier workers have suggested various reasons

for the heavy siltation in the lake and tried toexplain the deposition of trace metal ions (Cu, Co,Ni, Zn and Cr) which supply nutrients for thegrowth of aquatic weeds in Chilka. Lack of catch-ment basin management is one of the causes for theinCux of huge amounts of sediments in the lakewhich ultimately alters the ecology significantly(Panigrahi et al. 2007). According to Kumar et al.(2016), the main driving factors of the TSS aremonsoonal eAects, including precipitation andrunoA, wind-driven bottom re-suspension and riverdischarge into the lake. This river discharge is

mainly contributed by two major rivers, Daya andthe Bhargabi which are the distributaries of theMahanadi. The anthropogenic factor is responsiblefor the addition of nitrogen and phosphorouscompounds to the lake through drainage fromagricultural lands, especially paddy Belds (Pani-grahi et al. 2007). Panda et al. (2006) have docu-mented a rise in the concentration of differentmetal ions in the lake along with the deposition ofsand, silt and clay. Barik et al. (2020) have sug-gested that the major elements in the lake arederived from the weathering of the parent rock andwere later transported by the rivers (mainly by thedistributaries of the Mahanadi).However, the possible role of neotectonic activity

in causing the heavy siltation in the Chilka lake hasso far not been investigated. In this study, weexplore this possibility through an integrated studyof gravity, magnetic and morphotectonic data inthe area.

2. Location and geology of the study area

The study area encompasses the part of theMahanadi river passing through the EasternGhats in the northwest (Satkosia Gorge) and thesouthern part which includes part of coastalOdisha (Bgure 2). The southern part of the studyregion is traversed by the rivers Bhargabi, Daya,Mandakini and Ratnachira which are all dis-tributary channels of the River Mahanadi, andBnally, Cow into the Chilka Lake. However, RiverMandakini Cows almost in a straight trajectory ata high angle to the general trajectories of the other

Table 1. The earthquake details of most of the epicentres mark in Bgure 1. The date and place of the epicentres are taken from thesite (http://asc-india.org/seismi/seis-orissa.htm). The serial number corresponds to the serial number marked in Bgure 1.

Sl. no. Year Date Latitude Longitude Imax Magnitude Depth (km) Place

1 1837 15th June 19.5 85.1 VI Rambha–Paluru area

2 1858 16th March 21.5 87 V Baleshwar–Chandipur area

3 1860 25th February 19.4 84.9 V Karantola area

4 1891 17th June 20.8 87 V Near Palmyras Point

5 1963 8th May 21.7 84.9 5.2 33 Bijakuli–Banei area

6 1979 5th August 22.1 84.9 4.7 Jharkhand–Odisha border

7 1982 8th April 18.5 86.31 5.2 24 Bay of Bengal

8 1982 14th October 20.39 84.42 4.7 Khajuripada–Banigochha area

9 1985 1st July 18.367 87.188 5.4 10 Bay of Bengal

10 1995 27th March 21.671 84.565 4.6 10 Laimura–Deogarh area

11 1995 21st June 21.78 85.327 4.7 33 Kasijodi–Nuakot area

12 2001 12th June 22.24 83.918 4.7 25.5 Konokjora–Sundargarh area

J. Earth Syst. Sci. (2021) 130:220 of 20 220

rivers before joining the Daya river (Bgure 2). TheDaya and Bhargabi rivers form an anastomosingpattern on the downstream side which consists ofseveral multi-channels surrounding island bars.River Daya Cows towards the southwest andbifurcates into two branches near Motari. Thetrajectory of the main Cow is along the north-western side leaving the anabranch in the south-east. Similarly, the River Bhargabi also Cowstowards the southwest and is diverted towards thenorthwest before debouching into Chilka Lake.

The Bhargabi river forms its anabranch Rat-nachira on the northwestern side and itself Cowsin the southeast direction. Thus, for convenienceof analysis, two small regions designated as C1(located in the northern side of the study area)and C2 (located in the southern side) in Bgure 2are selected. C1 comprises the part of the Maha-nadi river in the Satkosia Gorge which Cowsthrough a part of the Eastern Ghats covered bythe Satkosia forest, while the C2 region is tra-versed by the Mandakini, Daya and Bhargabi

Figure 2. The geological map of the study region shows the various litho types, subsurface ridges and depressions, faults anddrainage systems (modiBed after Behera et al. 2004 and Nayak et al. 2006). The study region in Odisha comprises C1 and C2,where C1 is located on the northern side and C2 is located on the southern side.


rivers, of which the latter two debouch into theChilka Lake (Bgure 2).The Chilka Lake stretches from southeast of

Puri district up to the Ganjam district of Odishaand is bound by the Mahanadi delta region in thenortheast, the Eastern Ghats to the west andsouth, and barrier spits in the east. Venkatarath-nam (1970) studied the geomorphology of the spitpresent in the eastern part of the lake. The spit isaround 61 km long and 150 m wide and has an inletwhich narrows down from 1.6 km to just 15 m atpresent. Venkatarathnam (1970) divided the spitmorphologically into three regions – seawardbeach, dune belt and an inner aeolian Cat. Sandgrains in the seaward beach are coarse in natureand consist of heavy minerals like garnet as well assillimanite. In the north and northeastern part ofthe lake, khondalites, charnockites, granites andgneisses of the Eastern Ghats Belt are exposedalong the Mahanadi basin (Behera et al. 2004). Thebasement of the eastern coastal plain is coveredwith Gondwana sediments (both upper and lower),and then overlain by recent alluvium. The lowerGondwana (Talcher) and upper Gondwana (Ath-garh) sediments are exposed along the banks of theMahanadi river. The subsurface basement hashorst-graben structures represented by NE–SWtrending depressions (Konark, Paradeep and Ken-drapara depressions) alternating with ridges(Baishya and Singh 1986; Kaila et al. 1987; Fuloria1993; Behera et al. 2004). Based on the aeromag-netic data (Bgure 2), Nayak et al. (2006) showedthat various sets of lineaments/faults trendingalong ESE–WNW, NW–SE and N–S directionscontrol the trajectories of distributaries of theMahanadi river system.

3. Methodology

Satellite data such as Landsat 7 ETM+ andSRTM30 are collected from the USGS site(https://earthexplorer.usgs.gov/). Subsequentlypre-processing of data and image manipulationtechniques have been applied. The manipulationtechnique helps us to interpret the imagery moreclearly so that we can easily delineate the surBcialfeatures. Finally, the features identiBed from thesatellite imagery are checked through Beld valida-tion. Subsurface features have delineated from thegravity as well as magnetic data and later corre-lated with Cuvial geomorphic features interpret theoverall neotectonic scenario of the region.

3.1 Image manipulation techniques

The atmospherically corrected Landsat 7 ETM+data are converted into reCectance (Jana et al.2018). Subsequent to that various image manipula-tion techniques like band combination and bandratio are used to enhance the particular features.The Chilka Lake and its surrounding region com-prise wetland along with total suspended matter(TSM) and aquatic weeds. So, various multispectralindices and sub-pixel type image classiBcationtechniques like Linear Spectral Unmixing methodare applied to visualize the spatial distributionof wetland, TSM and aquatic weeds in the lake aswell as its surrounding region. In this case, NDVIor normalized difference vegetation index andMNDWI or modiBed normalized difference waterindex are used to enhance the signature of vegetationand water bodies, respectively (Jana et al. 2018).The quantiBcation of TSM and aquatic weeds areexecuted by running linear spectral unmixing (LSU)algorithm in the software ENVI 5.1. The LSU isbased on the following mathematical relationship:

ri ¼Xn

j¼1

ðaijxjÞ þ ei; ð1Þ

where ri is mean spectral reCectance for the ithspectral band of a pixel containing one or morecomponents, aij the spectral reCectance of the jthcomponent in the pixel for ith band, xj is the fractionof jth component in the pixel, ei is the error for the ithband, j = 1, 2, 3,…, n is the number of componentsand i is the number of spectral bands (Shimabukuroand Smith 1991). The TSM concentration has cor-relation with band 3 of wavelength 0.63–0.69 lm(Zhou et al. 2006) and vegetation is enhanced inNDVI (Jana et al. 2018), so these two componentsare used in collecting the pure pixels/endmembers(i.e., those pixels predominantly composed of a sin-gle component). Thus, for collecting pure pixels,corner pixels are chosen from the 2-D scatter plotgraph with NDVI as one axis (for vegetation) andband 3 as the other axis (for TSM). The extractedendmembers are used to execute LSU to Bnd thespatial distribution of TSMand aquatic weeds in thewetland region of the Chilka area (Bgure 3).

3.2 Lineaments/faults extractionand geomorphic analysis

SRTM data of 30 m resolution was collected in andaround Satkosia Region (marked by C1 in Bgure 2).


The directional Bltration has been applied to theelevation data in order to distinguish various setsof lineaments/faults and to get the 3-D view of theSatkosia area. These delineated lineaments/faultsare later correlated with the faults inferred fromgeophysical data. The geomorphic parameters playan important role in analysing neotectonic activity,which inCuences the change in Cuvial featuressuch as valley width/height ratio (Vf), mountainfront sinuosity (Smf ), basin asymmetry (AF ) andtransverse topographic symmetry (T ), and com-pressed meander (Wells et al. 1988; Keller andPinter 2002; Silva et al. 2003; Jain and Sinha 2005;Malik and Mohanty 2007; Kothyari and Rastogi2013; Roy and Sahu 2015; Bhattacharjee et al.2016). In the present work, these geomorphicparameters are applied to the Mahanadi distribu-taries which debouch into the Chilka Lake. A brief

description of each of the above proxy geomorphicparameters is given below.

3.2.1 Valley width/height ratio (Vf) andmountain front sinuosity (Smf)

The study region is in the northern side of theChilka area encompassing the part of the Maha-nadi river crossing through deep gorges of theEastern Ghats. The geomorphological indexes areextensively used in various countries like USA,Costa Rica, Spain and Taiwan to predict the neo-tectonic activity (Bull and McFadden 1977;Rockwell et al. 1984; Wells et al.1988; Rhea 1993;Chen et al. 2003; Silva et al. 2003). In India alsogeomorphological parameters are used in theKachchh region of Gujarat and in the Himalayan

Figure 3. The classiBcation map of Chilka Lake shows the distribution of the wetlands, total suspended matter (TSM) andaquatic weeds; (a) The water index or modiBed normalized difference water index (MNDWI) map of the Chilka region reveals thepresence of wetland in the northeast part as bright areas (marked by red dashed circle); (b) The vegetation map of the lake,overlapped on water index map shows the presence of high percentage of aquatic weeds in the northeastern side than in thecentral or southwestern side; (c) The TSM map shows the high percentage of sediments in the northeast side than central orsouthwestern side; (d) The Cowing pattern of the high percentage of TSM is visible in the northeast side and suggests that thesediments are mainly contributed from the northeastern side.


frontal regions (Sohoni et al. 1999; Malik andMohanty 2007) to understand the neotectonicactivities. In the present paper, two parameterslike valley width/height ratio (Vf) and mountainfront sinuosity (Smf ) are applied to a small part ofthe Mahanadi river to determine if the uplift of theEastern Ghats is a recent phenomenon or whetherit occurred in the geologic past. The parameter Vf

reveals if the river is actively downcutting andincising the basement due to uplift of the block.The Vf can be represented by simple mathematicalrelations (Bull and McFadden 1977; Keller andPinter 2002; Kothyari and Rastogi 2013)

Vf ¼2Vfw

Eld� Escð Þ þ Erd� Escð Þð Þ ; ð2Þ

where Vfw signiBes valley Coor width, Eld and Erdare elevations of left and right valley, dividesrespectively, and Esc is the elevation of the valleyCoor (Bgure 4a–c).The low value of Vf (\1) represents a narrow-

deep valley and the larger value of Vf ([1) signiBesbroad valleys (Wells et al. 1988; Keller and Pinter2002). Malik and Mohanty (2007) suggest aboutongoing tectonic activity based on the Vf value\1–1.5 in the Himalayan region. In the presentstudy, nine elevation proBles are drawn across theMahanadi river to get information on the height ofthe river banks, valley Coor as well as width of thevalley Coor for calculating Vf. The calculatedparameters for all the proBles drawn on SRTM (30)data are given in table 2. The proBles are drawn onthe Bltered image generated from SRTM data ofthe Mahanadi valley (Satkosia Gorge). Themountain front sinuosity index (Smf) is a measureof the degree of irregularity or sinuosity at the baseof a mountain where there is a break in slope. Inthe region where there is recent uplift throughtectonic activity, the mountain front (the line ofmeeting of mountain and the plain land) is almost astraight line or shows less irregularity. On theother hand, in regions that have not experiencedtectonic activity in the recent past, the mountainfront becomes incised or more irregular due toerosion by rivers or rainwater Cowing from themountain top. Mathematically this mountain frontsinuosity index can be shown by the relation:

Smf ¼ Lmf =Ls; ð3Þ

where Lmf is the length along the topographicmountain front andpiedmont, andLs is the straight-line length of the mountain front (Bull and

McFadden 1977; Keller and Pinter 2002; Malik andMohanty 2007). In the active tectonic region, thisSmf value is low (\1.6), while in a less active tectonicregion the Smf will have higher values (Bull andMcFadden 1977; Rockwell et al. 1984; Wells et al.1988; Rhea 1993; Sohoni et al. 1999; Silva et al.2003). Smf has been calculated along the SatkosiaGorge in the C1 area. In order to identify themountain front, False Colour Composite (FCC)technique was applied to the same area by taking acombination of different bands (4, 3 and 2) from theLandsat ETM+ 7. This FCC image will help todistinguish vegetation from water bodies. Thus, hillranges covered with dense vegetation can easily beidentiBed from the FCC image. The mountain frontis therefore identiBed from the FCC image and fromwhich Smf has been calculated as shown inBgure 4(d).

3.2.2 Basin asymmetry

This is another geomorphological proxy parameterwhich measures the degree of the symmetry of abasin. Assuming the region is under the samelithology and climatic conditions, the river tends toform a symmetrical basin. However, due to activetectonics, the river shows an abnormality in itsdegree of symmetry. Mathematically it may beshown by the simple ratio

AF ¼ 100� Ar=Atð Þ; ð4Þ

where AF is the degree of symmetry, Ar is the areaof the right side of the basin (looking at themainstream in the downstream direction) and At isthe total area of the basin (Keller and Pinter 2002;Kothyari and Rastogi 2013; Roy and Sahu 2015).In the present region, this parameter has beenapplied to the Mandakini river, whose tributarieshave been mapped from the SRTM30 data on theGIS platform. Later, these have been checked withthe high-resolution Google Earth image and theMNDWI map (Bgure 5a).

3.2.3 Transverse topographic symmetry (T)

The tectonic tilt of the basin can be estimated byanother parameter known as transverse topographysymmetry. Mathematically it can be expressed as

T ¼ Da=Dd; ð5Þ

where Da is the distance between the basin midlineand the main channel and Dd is the distance


between the basin midline and the water divide atthe periphery of the basin. In the case of the per-fectly symmetrical basin with no tectonic activityT = 0 and T = 1 in case, there is highly tectonic

activity (Keller and Pinter 2002; Kothyari andRastogi 2013; Roy and Sahu 2015). For the presentstudy purpose, Bve T values were calculated alongthe Mandakini river (Bgure 5a).

Figure 4. (a) The valley width–height (Vf) ratio is shown schematically. All the variables taken in calculating the Vf value aredescribed in the text; (b) The Vf values are calculated for the proBles drawn across the Mahanadi river (C1 region in Bgure 2);(c) The Vf values are found to be low (\1.5) in the Satkosia Gorge (marked by a red rectangle) and suggest valley undercuttingdue to basement uplift. The Vf values are more than 1.5 in north and south of Satkosia Gorge; (d) The mountain front sinuosity(Smf ) or ratio of Lmf to Ls along the mountain front in the vicinity of Satkosia Gorge shows low irregularity in the frontal lineand suggest the probable recent uplift.


3.2.4 Compressed meander

River channels have a tendency to become asym-metric at river bends and develop high anomaloussinuosity due to tectonic disturbance. This type ofasymmetry in river bends caused by conBnement ofthe river to a limited area as a result of the tectoniccompression is known as compressed meander(Jain and Sinha 2005). In the Chilka region,satellite imagery like Google Earth and LandsatETM+ have been used to identify compressedmeanders of the channels Cowing to the ChilkaLake (Bgure 5b). The river trajectories have beentraced from the high-resolution Google Earthimage and are shown in Bgure 5(b).

3.3 Geophysical study

Geophysical study is required in order to identifysubsurface features. Subsequently the resultsobtained from the geomorphological study arecorrelated with results obtained from geophysicalstudies to understand the overall tectonics occur-ring in the region. In the present analysis, thegravity as well magnetic data are collected duringthe Beld survey in and around Chilka Lake and areprocessed to get the anomaly map.

3.3.1 Gravity study

The basement rock, overlain by thick sediments isuplifted in some parts and subsided in other partsand so the sediment thickness varies from place toplace. This inCuences the overall mass of theblock or in other words the variation in bulkdensity inCuences the gravity values. This

difference in gravity is recorded in the gravimeterto get an idea about the relative displacement ofthe block along the fracture planes. In the presentstudy region (marked by C2 in Bgure 2), we haveused W. Sodin Gravimeter with the precision of0.01 mGal to collect the relative variation ofgravity from one place to another. Reduction ofgravity data is carried out applying latitude cor-rection, free air correction (FA) and Bouguer slabcorrection (BS). Before the reduction of gravitydata, drift corrected gravity data are tied up withthe base station for the assignment of absolutevalue. Thus, Bouguer anomaly (BA) is calculatedusing the following algebraic relation (Telfordet al. 1990)

BA ¼ Gobs�Gthð Þ þ FA�BS �L; ð6Þ

and the contour map is generated. However, due tosparse Beld data, in the C1 sector which encom-passes the MSZ (marked in Bgure 2), the Bougueranomaly values from the GSI-NGRI map (2006)have been used and later digitized on the GISplatform to generate the anomaly map (Bgure 6a).

3.3.1.1 Regional–residual separation: The Bou-guer anomalies represent the contributions of allthe density inhomogeneities lying at differentdepths below the ground surface. Therefore, it isessential to separate out the anomaly contributionsfrom shallow sources (known as residual anomaly)from sources that are deep-seated origin (known asregional anomaly).In the present context, the shallow subsurface

structures are instrumental in controlling the riversystem, and so the mapping of these features isimportant. These features can be delineated fromthe residual anomaly map, which is generatedfrom the residual values. The residual values areseparated by removing regional values from theBouguer anomaly values (Telford et al. 1990). Inthe present study, regional values are calculatedthrough trend surface analysis by solving thecoefBcients of a 3rd order polynomial equation (asit represents the best Btted polynomial curve)through the execution of MATLAB programmingcode (Mandal 2013; Mandal et al. 2015) (Bgure 6b).Finally, the trajectories of the rivers Bhargabi,Daya and their anabranches are overlapped on theresidual gravity anomaly map of the Chilka regionto determine the spatial relationship between thehigh–low anomaly boundary zones (which repre-sent the suspected faults) and the rivers.

Table 2. The Valley width–depth ratio (Vf values) of the dif-ferent proBles drawn across the Mahanadi River near SatkosiaGorge. The short terms of the parameters are described in thetext.

ProBles Eld (m) Erd (m) Esc (m) Vfw (m) Vf

M1 839 438 71 9486 16.72

M2 750 470 115 11434.1 23.10

M3 376 318 86 6175.4 23.66

M4 600 863 55 392.6 0.58

M5 553 446 55 440.2 0.99

M6 495 740 55 328.2 0.58

M7 501 501 55 555 1.24

M8 622 753 55 396.2 0.63

M9 280 308 56 3781.2 15.89


3.3.2 Magnetic method

The subsurface rocks have various magnetic prop-erties due to Earth’s magnetic Beld so a magneticsurvey is done to investigate the various subsurfacebasement rocks which retain different magneticelements. A major contribution of magnetic sig-natures comes from basement rocks. Uplift andsubsidence of basement rocks can also be identiBedusing the magnetic method. On the earth, bothnonmagnetic and magnetic minerals are present,but magnetic minerals forming the rocks show

various magnetic anomalies which are detected

during the magnetic survey. Igneous bodies are

commonly emplaced along weak zones such as fault

planes. Thus the trend of the fault planes can bedelineated from the magnetic anomaly contourelongations, nosings, Cexures and tight and dif-fused bandings (Nayak et al. 2006). In the presentcontext, magnetic survey is done in and aroundChilka Lake (C2) by a Proton-precession magne-tometer which measures the total Beld of a region.The magnetic data are collected along the roadsideat 2 km intervals and are processed for variouscorrections including International GeomagneticReference Field (IGRF) correction. Reduced-to-pole transformation (RTP) is applied to magneticdata to remove the asymmetric nature of magneticanomalies produced due to the bipolar nature ofthe magnetic bodies (Mohanty et al. 2011; Mandal

Figure 5. (a) The basin asymmetry and transverse topographic symmetry (T) are calculated from the delineated basin of theMandakini river. The Bgure depicts that the left part of the basin (Al) has relatively more area than the right part of the basin(Ar) and it suggests probable tilting of the basin towards the south. All the T values are[0 which suggests the overall shifting ofthe Mandakini river towards the south (shown by arrows) from the basin midline probably due to tectonic tilting; (b) The Dayaand Bhargabi rivers show the asymmetric or compressed meander as evidence of tectonic disturbance.


2013). Finally, to detect the shallow surface mag-matic bodies, the corrected magnetic data are usedto get residual data by removing the regional val-ues through trend surface analysis (Bgure 6c).

3.3.3 3-D inversion model

The Bouguer anomaly value varies with the vari-ation of density of the subsurface structures andthe subsurface structures can be predicted based onthis density variation. The gravity model especially2-D/3-D compact inversion helps us to visualizethe vertical and the lateral extension of the geo-logical bodies in the subsurface (Last and Kubik

1983). So to view the density distribution based onthe Bouguer anomaly values, the 3-D compactinversion process is executed using MATLABprogramming language (Mandal 2013; Mandalet al. 2015). In the inversion process, there are fewsteps, at Brst, the region is gridded with numerousblocks having dimensions along x, y and z direc-tions. Subsequent to this, the density contrast ofeach block is calculated repeatedly until thedesired density contrast is obtained with minimumerror to Bt with the observed anomaly curve. Inthis study, the 3-D compact inversion model hasbeen generated from the residual gravity anomaly(which is extracted from Bouguer anomaly values)in the Chilka region (Bgure 7). The subsurface 3-D

Figure 6. (a) The Bouguer anomaly of the study region C1 (marked by the rectangle) comprising Satkosia Gorge shows arelatively high anomaly in the downstream part of the Mahanadi river in the southeastern side and a low anomaly in thenorthwest part. The high–low anomaly boundary is followed by the trend of the Mahanadi Shear Zone or MSZ (MSZ is mappedafter Bose and Gupta 2018); (b) The residual gravity anomaly map of the C2 region of the study area shows alternate high–lowanomaly values possibly due to underlying uplift-depression zones. The suspected faults are marked by arrows on the high–lowanomaly boundary zones that control the trajectories of Mandakini, Daya and Bhargabi rivers. The trend of the extended part ofthe MSZ (mapped after Rao et al. 2015) is matching with the delineated NW–SE faults suggest these are part of MSZ; (c) Themagnetic anomaly map also shows a similar type of fault sets identiBed from the gravity anomaly map.


model gives an overview of the density distributionof the various lithologies. The average density ofthe crust is taken as 2670 kg/m3 (average densityof the upper crust) while keeping the maximum aswell as the minimum density as 3070 kg/m3 (thedensity of basic rock) and 1870 kg/m3 (density ofthe alluvium), respectively. Apart from thesecomponents subsurface of the coastal region alsocomprises Gondwana sediments (2400 kg/m3), aswell as Tertiary sediments (2200 and 2350 kg/m3)as reported by Behera et al. (2004) based ongravity data; the density values used in this studylies within this range. Four proBles namely MM1,NN1, QQ1 and RR1 were selected across the

suspected faults (Bgure 7) from the generated 3-Dinversion density model.The residual anomalies of these regions reveal

horst-graben structures which were intruded byhigh-density materials (as seen from magneticanomaly also).

4. Results

4.1 Image interpretations

The MNDWI map of the study region (here C2 inBgure 2) shows bright areas over the Chilka Lakeand the existing rivers. These bright areas are

Figure 7. (a–d) The proBles (MM1, NN1, QQ1 and RR1 marked in Bgure 6a) of the 3-D depth inversion model reveal the uplift-depression zones bounded by steep faults; (e) The 3-D inversion model shows both vertical and plan view of this uplift-depressionzones in the subsurface of the study region.


interpreted to be water bodies which include rivers,lakes and the wetlands. It is to be noted that theexisting rivers and their distributaries are muchbrighter than the paleochannels which show rela-tively low brightness (Bgure 3a). After comparingwith a high-resolution image of Google Earth,shifting of the channels of the rivers Daya andBhargabi can be identiBed. These shifts are evi-denced from the presence of abandoned channelsindicating Cow diversion of these rivers (Bgure 8a,b). The Daya river shows the sign of shiftingtowards the northwest and the imprints are left aspaleochannels (as seen from vegetation band andwater patches in the MNDWI map) near the rockexposure in Motari (Bgure 5b). The Bhargabi rivershows a sharp diversion towards the northwest

before debouching into the lake. It is to be notedthat some water bodies lie beyond the northeasternboundary of the lake, in the region between theserivers, which are predicted to be wetlands and areconBrmed after Beld validation (Bgures 8, 9). TheLSU algorithm identiBes the quantity of TSM andvegetation (aquatic weeds) within this wetland aswell as in the Chilka Lake. The percentage of TSMand weeds gradually decreases from the north-eastern side to the centre of the lake (Bgure 3b, c).The land surrounding the Chilka Lake containsexposure of metamorphic rocks as observed nearMotari suggesting the presence of basement atshallow depth. Satellite imagery also reveals theanastomosing nature of the Daya and Bhargabirivers where small paleo-island bars are joined

Figure 8. (a) The part of the water index or MNDWI map (deBned by the green rectangle in Bgure 3) shows the Cow diversion ofthe Daya river towards the west probably due to basement uplift leaving the imprints as paleochannels. The same observationsare found in high-resolution Google Earth image also; (b) Both the water index map (deBned by a yellow rectangle in Bgure 3)and the high-resolution Google Earth image reveals the Cow diversion of the Bhargabi river towards the north leaving the earlierremnant channels.


together to form larger paleo-island bars intercon-nected by abundant paleochannels which aredelineated with the help of earlier work of theauthors (Jana et al. 2016, 2018).

4.2 Lineaments/faults extractionand geomorphic study

The 3-D image obtained from SRTM data revealsNW–SE trending faults/lineaments parallel to theMahanadi Shear Zone (MSZ) along with variationsin the width of the Mahanadi valley (Bgure 4b). Inthe gorge area (marked by a red rectangle inBgure 4b) the river valley narrows down withoutforming any meander. The Vf values of the BveproBles (ProBles 4, 5, 6, 7 and 8) across the gorge

area of the Mahanadi are less than 1.5, while pro-Bles 1, 2, 3 and 9 in the extreme north-western andsouth-eastern sides of the gorge have values morethan 1.5 (Bgure 4c and table 2). The FCC imagereveals hill ranges densely covered with vegetationas red in colour which can be easily discerniblefrom the blue coloured Mahanadi river. Themountain front line can easily be detected from thetruncation of gullies against the plain land. Thecalculated Smf value along the Satkosia Gorge inthe northern part of the Eastern Ghats (calculatedfrom Bgure 4d), along the Mahanadi Shear Zone is1.041, which suggests neotectonic activity (Malikand Mohanty 2007). Thus, based on the Vf as wellas Smf values, the region along the Satkosia Gorgeis interpreted to be tectonically active. The

Figure 9. (a–b) The Chilka wetlands roamed by migratory birds are observed during our way to Satpada on the northeast side ofthe lake.


Mandakini river is also found to follow the NW–SEtrend of the Mahanadi Shear Zone. Moreover,tilting of the Mandakini Basin towards the south(as seen from basin asymmetry) also suggests thatthe region along the MSZ is tectonically active.The calculated basin asymmetry (AF) value isaround 28% (\50%) obtained by dividing the areaof the right side of the basin (Ar = 161.4 km2) bythe total area of the basin (At = 578.85 km2). Fivevalues of Transverse Topographic Symmetry(T) were measured along the channel, yieldingvalues of 0.27, 0.55, 0.59, 0.36 and 0.32 (average= 0.42 which is[0; Bgure 5a). Since, all the valuesof T are greater than 0, neotectonic activity can beinferred (Keller and Pinter 2002; Kothyari andRastogi 2013; Roy and Sahu 2015).

4.3 Geophysical study

The Bouguer anomaly map of the C1 area showsalternate high and low anomaly regions, with theirboundary roughly coinciding with the MSZ and thetrajectory of the River Mahanadi (Bgure 6a). Thenorthwestern part of the Mahanadi river is charac-terized by lower gravity anomaly values than thesoutheastern part. Since the lithological set-upacross both areas is similar (see geological maps inBose and Gupta 2018, 2020; Bose et al. 2020; Maitraet al. 2021), the higher gravity anomalies can only beexplained by a shallower depth to the basement inthe southeast. This suggests that the southeasternpart was uplifted even as the river was Cowing,causing the river to incise its valley along the Sat-kosiaGorge. In the residualmapof theC2 region, thepresence of alternating high (around 29 mGal) andlow anomaly values (around –26 mGal) suggest thepresence of uplifts and depressions within the base-ment at shallow depth. Generally, the inCection lineof a fault can be delineated along the transition oflow to high, or high to low anomaly points (Telfordet al. 1990). The presence of faults is also suspectedfrom the linear nature of the contours between thehigh and low anomaly zones in the residual anomalymap (Bgure 6b). These faults are seen to trendNW–SE, parallel to the Mahanadi Shear Zone(MSZ), while another set trends along a NE–SWdirection (Bgure 6b). These faults are possibly rela-ted to the MSZ, which extends along the NW–SEdirection to the north and northeast of Chilka Lake.The presence of faults in the C2 region is furtherevidenced from the magnetic anomaly map whichreveals the presence of highmagnetic anomaly zones

along the suspected faults that trend NW–SE(Bgure 6c). High magnetic anomalies indicate thepresence ofmaBcmagmatic bodies in the subsurface.In this case, the magnetic anomalies are also asso-ciated with high gravity anomalies, suggesting thatthe crustal basement was intruded by high-densitymaterial (q=*3070kg/m3),which canbe related toshallow magmatic bodies emplaced during an erup-tion of theRajmahalTraps around 117Ma, as earlierreported by Behera et al. (2004; Bgure 6c). Sincethese anomaly zones are bound by contacts betweenthe high and low gravity and magnetic anomalyzones, which are interpreted to be faults, thesemagmatic bodies are likely to have intruded throughthese weak zones and were emplaced at shallowdepth. The four proBles of the 3D inverse modelreveal alternating basement uplifts and depressionsbounded by steep faults; these basement structuresare overlain by low-density sediments (Bgure 7).

4.4 Combined study

The spatial relationship between the river trajec-tories and the delineated faults identiBed from theresidual gravity and magnetic anomaly maps andthe results of the 3-D gravity modelling help inassessing the tectonic history of the region. Whenthe rivers along with their paleochannels areoverlapped with the gravity anomaly map, inter-esting observations can be made. In the C1 region,the Mahanadi river is found to follow the trend ofthe Mahanadi Shear Zone. The river Cows over thebasement uplift in its southeastern (downstream)part, while its northwestern (upstream) part lieswithin the subsided region (Bgure 6a), which sug-gests that uplift of the basement took place afterthe origin of the river (Bgure 6a). In the C2 region,the Mandakini river is found to follow a lineartrajectory parallel to the suspected NW–SE faultbefore joining the Daya river in the east. The riverssuch as Daya and Bhargabi are controlled by thefaults marked in Bgure 6(b). It is found that all therivers Cow through the uplift-depression zone. TheDaya and Bhargabi rivers have uplifted zones intheir downstream segments, which suggest that inboth cases, the basement was uplifted after theorigin of these rivers. The linear trajectory andrectangular pattern of the rivers Mandakini andDaya suggest that the basement depth is shallow.This implies that the overlying thick alluvium hasa minimal role in shielding the eAect of basementuplift on the river trajectories of Daya as well as


Bhargabi. In Bgure 10, it is seen that both riversshow Cow diversion, leaving their paleochannelsstranded in the uplifted zone, while the existingrivers Cow through the depressed zone/or rela-tively less uplifted zone. This also suggests thatthere was tectonic tilting, which triggered theserivers to shift laterally towards the down tiltedregion. The rivers, while Cowing through theseuplift-depression structures in the basement,deposited sediments in the subsided zone and ero-ded the basement in the uplifted zone. Since thesubsided zone ultimately forms part of the present-day lake, the eroded sediments are ultimatelydeposited in the lake itself.

5. Discussion

The Himalayan Orogeny plays an important role ingenerating compressional stresses in different partsof the Indian Shield, as a consequence of which

seismic tremors occur in different regions. Suchseismic tremors frequently occur along older faults(mainly oriented NW–SE) or terrane boundaries,as found to the north of the Talcher Basin (Guptaet al. 2014). The basement of the coastal plain isalso traversed by different sets of faults, some ofwhich have connections with oAshore faults (Mur-thy et al. 2010; Rao et al. 2015). Thus, seismictremors which have epicentres in the Bay of Bengalmay also create seismic tremors in the adjoiningcoastal region. Many shear zones traverse the eastcoast of India, among which the MSZ is particu-larly important as it is a major tectonic structure inthe region (Murthy et al. 2010). Thus, the Maha-nadi Graben, which is bound by the MSZ in thesouth and the North Orissa Boundary Fault in thenorth, is fundamentally a weak zone (Mahalik2006; Rao et al. 2015). Therefore, the easternextension of the MSZ into the Chilka region(Maitra et al. 2021) is important for assessing

Figure 10. (a) The schematic diagram shows the controlling eAect of the delineated faults on the Daya river and the resultingriver avulsion within the region marked by a rectangle in Bgure 6(b); (b) The Bgure shows the controlling of the delineated faultson the Bhargabi river and the resulting river avulsion in the region marked by a rectangle in Bgure 6(b); (c) The Bgure shows thesectional view of the proBle (marked by red line in Bgure 10b), role of uplift-depression zones in sedimentation–erosion by therivers.


neotectonic activity in the region. Dhar et al.(2017) revealed the presence of two sets of neo-tectonic faults (oriented NE–SW and NW–SE) inthe proximity of the lake, which also coincides withsimilarly oriented linear features inferred fromgravity and magnetic data. Some of the NE–SWoriented neotectonic faults revealed by Dhar et al.(2017) bound the depression zones (i.e., theKonark, Paradeep and Cuttack depressions;Bgure 2). The NE–SW faults inferred from thegravity data are found to be extensions of theearlier delineated NE–SW neotectonic faults.Similarly, the NW–SE faults are probably part ofthe MSZ, which is itself a major tectonic feature.Hence, it is believed that both these sets of dis-criminant lines, interpreted from the gravity andmagnetic data, coincide with faults that areresponsible for the differential movement of base-ment blocks, and later controlled river trajectoriesin the Chilka region. In other words, these two setsof faults divide the basement into several blocks;later NE–SW directed compression led to uplift ofthe blocks as the NW–SE set was reactivated asreverse faults.

5.1 Reactivation of the Mahanadi Shear Zone

The MSZ trends in a NW–SE direction, and itsextension into the Chilka region is also evidencedfrom the gravity and magnetic anomaly map. It isobserved that the NW–SE trend of both gravityand magnetic anomaly patterns match well withthe trend of the MSZ shown by Rao et al. (2015)and Bose and Gupta (2018, 2020). The MahanadiGraben (which is bound by the MSZ in the south)also trends NW–SE and extends southeastwardinto the coastal plain as shown in Bgure 1(b) (Ma-halik 2006). Thus, the NW–SE trending faults(identiBed from gravity and magnetic anomalies),which divide the basement into separate blocks, areprobably extension of the Mahanadi Shear Zonesystem towards the southeast. The Cow of theMahanadi river through the Satkosia Gorge, whichis undergoing rapid uplift as evidenced from a lowmountain front sinuosity index and the high grav-ity anomaly in the downstream side, led to verticalincision of its valley, which now has low Vf values.This suggests that the southeastern segment of theMSZ was reactivated. Thus, the two sets of faults(NW–SE and NE–SW) along which magmaticbodies were emplaced during the eruption of theRajmahal Traps at *117 Ma (Baksi 1995; Behera

et al. 2004), control the present trajectories of therivers through this zone of basement uplift.

5.2 Heavy siltation in Chilka Lake

The high percentage of TSM in the northeasternpart of Chilka Lake suggests that these are derivedfrom the Daya and Bhargabi rivers. Mineralnutrients, along with TSM from the land, are car-ried into the lake by these rivers and help in thegrowth of thick aquatic weeds in the lake, as seenfrom the high percentage of vegetation in the veg-etation map (Bgure 3). Superposing the two riversDaya and Bhargabi on the gravity anomaly mapshows that their anastomosing pattern and com-pressed meanders overlap with the high gravityanomaly zone, suggesting that this may also be anuplifted zone. The trajectories of both these riversare controlled by faults such as AB, EF, GH, OPand XY, as brieCy described in Bgure 10. InBgure 10(a), on the upstream side, it is found thatthe River Daya Cows towards the southwest afterbranching oA from the Mahanadi river, but isdiverted towards the northwest due to uplift of theblock along the faults AB and OP, evidenced by aseries of shifting paleochannels, as observed inBgure 8a. Initially, the uplift of the block led to theriver eroding its basement, with the eroded sedi-ments depositing in the subsided part (Bgures 6band 10a). Later, further uplift of the block led tothe diversion of the channel towards the northwest,while the abandoned part of the river in the uplif-ted zone is left stranded as a paleochannel. Thepresence of angular (or compressed) meandersalong the river also suggests tectonic disturbance,which can be related to uplift caused by the com-pressional eAects of the Himalayan Orogeny.Figure 10(b) reveals how the downstream parts

of both the Daya as well as Bhargabi rivers arecontrolled by the two sets of faults (NW–SE andNE–SW). On the downstream side of the riverDaya, the block to the northeast of the lake isuplifted while the subsided part is represented bythe lake. This uplift and subsidence of the base-ment resulted from reactivation of both fault sets,leading to erosion of the uplifted block and sedi-mentation in the subsided part, which in turncauses increased siltation in the lake. The down-stream part of the River Bhargabi is also controlledby the faults EF, GH and XY marked inBgure 10(b). Initially, this river Cows towards thesouthwest to debouch into the lake. However,


uplift of the block to the south, between theNW–SE trending faults EF as well as GH, andNE–SW trending fault XY led to Cow diversion ofthe River Bhargabi towards the north, into thesubsided zone. As a result, the river left its earlierremnant part as paleochannels which are nowpreserved in the uplifted region (Bgure 10b, c). Thissuggests that the paleochannels of both rivers areformed due to tectonic reasons, rather than normalmeandering or climate change. Thus, it can besummarized that due to uplift and subsidence ofbasement blocks because of periodic reactivation ofthe NW–SE and NE–SW trending faults, the riversundergo sedimentation in the subsided zones anderosion in the uplifted blocks. This results in thedeposition of large volumes of eroded sediments inthe lake. Besides these, seismic tremors of low tomoderate intensity in the Berhampur–Jankia zone,and in the proximity of NE–SW faults in the studyregion, are also manifestations of the neotectonicactivity in this region (Bgure 1).

6. Conclusions

This study attempts to address the problem ofheavy siltation taking place in present-day ChilkaLake from the perspective of neotectonic activity.Although there are several other causes (includinganthropogenic) for the heavy siltation in the lake,neotectonic activity can explain heavy sedimenta-tion over a long term. The study also shows aninterconnection between geomorphic and subsur-face structures. Geophysical studies in the areareveal a number of gravity as well as magnetichighs and lows that can be separated by linearNW–SE and NE–SW trending zones on the map.Since the lithological set-up is similar along theMahanadi, the gravity and magnetic anomalies areattributed to uplifts and depressions in the sub-surface basement. The NW–SE trends also corre-spond to relatively linear segments of theMahanadi and Mandakini rivers; these segmentscan be interpreted as faults that reactivated pre-existing faults and shear zones associated with theancient Mahanadi Shear Zone (MSZ). Along theMahanadi, the NW–SE oriented Satkosia Gorgesegment is characterized by a steep linear scarpwith low Vf and Smf values indicative of neotec-tonic activity, as the river continues to Cow over asteadily uplifting zone (characterized by the highgravity anomaly), vertically incising its basementin the process. The trajectory of the River

Mandakini and the longitudinal axis of its basin isalmost similar to the trend of MSZ. Uplift alongone side of the MSZ led to lateral shifting of theMandakini, resulting in basin asymmetry and anincrease in the value of T to greater than zero. Nearthe Chilka Lake, the courses of the Daya andBhargabi rivers have also altered along contactsbetween high and low gravity anomaly zones; thesecontacts also trend NW–SE or NE–SW. Thegravity highs and lows are interpreted as upliftsand depressions in the basement, and their con-tacts are interpreted to be reactivated faults, sim-ilar to that seen further upstream in the case of theMahanadi and Mandakini. Indeed, the present-dayriver course is diverted through the low anomalyzones (basement depressions), while the highgravity anomaly zones contain abandoned pale-ochannels, testifying to the changing courses of therivers as the basement blocks were uplifted. Seis-mic tremors are associated with all these faults,further testifying to ongoing neotectonic activity.Reactivation of these basement faults is ascribed tothe release of compressional stresses accumulatingwithin the Indian Shield on account of the Hima-layan Orogeny, which results in the formation ofuplifts and depressions in the basement of thisregion. The basement depressions are associatedwith, and continue into Chilka Lake; as uplift ofthe adjoining blocks continues, material erodedfrom these blocks is deposited in the lake, leadingto the presently observed heavy siltation.

Acknowledgements

The authors would like to thank US GeologicalSurvey for providing free satellite data for researchpurposes. This work is a part of a larger projectbeing undertaken under the SANDHI initiative atIIT Kharagpur, funded by the Ministry of HumanResource Development (now Ministry of Educa-tion, Government of India). The authors would liketo thank the Ministry of Education for the funding.

Author statement

SJ conducted all the technical study, includingcollection and processing of geophysical data andall image processing and interpretation. WKMcontributed to interpretation and analysis andsupervised the entire study. PK was associatedwith geophysical data collection and processing.


SG contributed in the Beld, data interpretation andwriting of the Bnal version.

References

Anand S P and Rajaram M 2004 Crustal structure ofNarmada–Son lineament: An aeromagnetic perspective;Earth, Planets Space 56(5) 9–12.

Baksi A K 1995 Petrogenesis and timing of volcanism in theRajmahal Cood basalt province, northeastern India; Chem.Geol. 121 73–90.

Baishya N C and Singh S N 1986 DSS proBling in Mahanadionshore areas: A case study; In: Deep Seismic Soundingsand Crustal Tectonics (eds) Kaila K L and Tewari H C,Assoc. Explor. Geophys., Hyderabad, India, pp. 1–9.

Banerjee P, Burgmann R, Nagarajan B and Apel E 2008Intraplate deformation of the Indian subcontinent; Geo-phys. Res. Lett. 35(18) 1–5.

Barik S S, Prusty P, Singh R K, Tripathy S, Farooq S H andSharma K 2020 Seasonal and spatial variations in elementaldistributions in surface sediments of Chilika Lake inresponse to change in salinity and grain size distribution;Environ. Earth Sci. 79(269) 1–18.

Behera L, Sain K and Reddy P R 2004 Evidence ofunderplating from seismic and gravity studies in theMahanadi delta of eastern India and its tectonic signifi-cance; J. Geophys. Res. 109 1–25.

Bharali B, Rath S and Sarma R 1991 A brief review of Mahanadidelta and the deltaic sediments in Mahanadi basin: Quater-nary deltas of India; Mem. Geol. Soc. India 22 31–49.

Bhattacharjee D, Jain V, Chattopadhyay A, Biswas R H andSinghvi A K 2016 Geomorphic evidences and chronology ofmultiple neotectonic events in a cratonic area: Results fromthe Gavilgarh Fault Zone, central India; Tectonophys.677–678 199–217.

BIS 2002 IS1893–2002 (Part 1): Indian Standard Criteria forEarthquake Resistant Design of Structures, Part 1 –

General Provisions and Buildings, Bureau of Indian Stan-dards, New Delhi.

Bose S, Das A, Samantaray S, Banerjee S and Gupta S 2020Late tectonic reorientation of lineaments and fabrics in thenorthern Eastern Ghats Province, India: Evaluating therole of the Mahanadi Shear Zone; J. Asian Earth Sci.201(104071) 1–18, https://doi.org/10.1016/j.jseaes.2019.104071.

Bose S and Gupta S 2018 Strain partitioning along theMahanadi Shear Zone: Implications for paleo-tectonics ofthe Eastern Ghats Province India; J. Asian Earth Sci. 157269–282, https://doi.org/10.1016/j.jseaes.2017.11.021.

Bose S and Gupta S 2020 Evolution of stretching lineations ingranulite-hosted ductile shear zones, Eastern Ghats Pro-vince, India: Role of temperature, strain rate and pre-existing stretching lineations; J. Struct. Geol. 138 104127,https://doi.org/10.1016/j.jsg.2020.104127.

Bull W B and McFadden L D 1977 Tectonic geomorphologynorth and south of the Garlock fault, California; In:Geomorphology of Arid Regions (ed.) Doehring D O,Proceedings of the Eighth Annual Geomorphology Sympo-sium, State University of New York at Binghamton,Binghamton N, pp. 115–138.

Chen Y C, Sung Q and Cheng K Y 2003 Along-strike variationsof morphotectonic features in the Western Foothills ofTaiwan: Tectonic implications based on stream-gradient andhypsometric analysis; Geomorphology 56 109–137.

Dhar S, Rai A K and Nayak P 2017 Estimation of seismichazard in Odisha by remote sensing and GIS techniques;Nat. Hazards 86 695–709.

Fuloria R C 1993 Geology and hydrocarbon prospects ofMahanadi basin, India; In: Proceedings of the SecondSeminar on Petroliferous Basins in India (ed.) Biswas S Ket al., Indian Petrol., Dehradun, India 1 355–369.

Gupta S, Mohanty W K, Mandal A and Misra S 2014 Ancientterrain boundaries as probable seismic hazards: A casestudy from the northern boundary of the Eastern GhatsBelt India; Geosci. Front. 5 17–24.

GSI-NGRI 2006 Gravity anomaly map of India on 1:2 millionscale, Geological Survey of India, Hyderabad and NationalGeophysical Research Institute, Hyderabad, India, Maps,pp. 1–3.

Jade S 2004 Estimates of plate velocity and crustal deforma-tion in the Indian subcontinent using GPS geodesy; Curr.Sci. 86(10) 1443–1448.

Jain V and Sinha R 2005 Response of active tectonics on thealluvial Baghmati River, Himalayan foreland basin, easternIndia; Geomorphology 70 339–356.

Jana S, Mohanty W K, Gupta S, Rath C S, Behera R R andPatnaik P 2016 Multi-pronged search for paleo-channelsnear Konark temple, Odisha: Implications for the mythicalriver Chandrabhaga; Curr. Sci. 111 1387–1393.

Jana S, Mohanty W K, Gupta S, Rath C S and Patnaik P 2018Palaeo-channel bisecting Puri Town, Odisha: Vestige of thelost river ‘Saradha’?; Curr. Sci. 115(2) 300–309.

Kaila K L, Tewari H C and Mall D M 1987 Crustal structureand delineation of Gondwana sediments in the Mahanadidelta area, India, from deep seismic soundings; J. Geol. Soc.India 29 293–308.

Keller E A and Pinter N 2002 Active Tectonics: Earthquakes,Uplift and Landscape (2nd edn), Prentice Hall, New Jersey,361p.

Kothyari G C and Rastogi B K 2013 Tectonic control ondrainage network evolution in the upper Narmada Valley:Implication to Neotectonics; Geography J. 2013 1–9.

Krishna K S, Bull J M and Scrutton R A 2001 Evidence formultiphase folding of the central Indian Ocean lithosphere;Geology 29(8) 715–718.

Krishna K S, Bull J M and Scrutton R A 2009 Early (pre-8Ma) fault activity and temporal strain accumulation in thecentral Indian Ocean; Geol. Soc. America 37(3) 227–230.

Kumar A, Equeenuddin Sk Md, Mishra D R and Acharya B C2016 Remote monitoring of sediment dynamics in a coastallagoon: Long term spatio-temporal variability of suspendedsediment in Chilika; Estuar. Coast. Shelf Sci. 170 155–172.

Last B J and Kubik K 1983 Compact gravity inversion;Geophysics 48 713–721.

Maitra A, Bose S, Ghosh A and Gupta S 2021 Neoproterozoicextension and decompression in the northern Eastern GhatsProvince, India: Mid-crustal signature of Rodinia break-up?; Precamb. Res. 358 106149, https://doi.org/10.1016/j.precamres.2021.106149.

Mahalik N K 2006 Geology and Mineral Resources of Orissa(3rd edn), Bhubaneswar 751 001; Society of Geoscientistsand Allied Technologies, Odisha, pp. 27–44.


Malik J N and Mohanty C 2007 Active tectonic inCuence on theevolution of drainage and landscape: Geomorphic signaturesfrom frontal and hinterland areas along the NorthwesternHimalaya, India; J. Asian Earth Sci. 29 604–618.

Mandal A 2013 Integrated geophysical studies for delineationof subsurface structures and mineral deposits in the easternIndian shield, PhD diss., Dept. of Geology and Geophysics,IIT Kharagpur, Kharagpur.

Mandal A, Gupta S, Mohanty W K and Misra S 2015 Sub-surface structure of a craton–mobile belt interface: Evi-dence from geological and gravity studies across the RengaliProvince–Eastern Ghats Belt boundary, eastern India;Tectonophys. 662 140–152.

Mohanty W K, Mandal A, Sharma S P, Gupta S and Misra S2011 Integrated geological and geophysical studies fordelineation of chromite deposits: A case study from Tan-garparha, Orissa, India; Geophysics. 76(5) B173-185.

Murthy K S R, Subrahmanyam V, Subrahmanyam A S,Murty G P S and Sarma K V L N S 2010 Land-oceantectonics (LOTs) and the associated seismic hazard overthe Eastern continental margin of India (ECMI); Nat.Hazards 55 167–175.

Nayak G K, Rao C R and Rambabu H V 2006 Aeromagneticevidence for the arcuate shape of Mahanadi Delta, India;Earth Planets Space 58 1093–1098.

Panda U C, Rath P, Sahu K C, Majumdar S and Sundaray S K2006 Study of geochemical association of some trace metalsin the sediments of Chilika Lake: A multivariate statisticalapproach; Environ. Monitor. Assessment 123 125–150.

Panigrahi S, Acharya B C, Panigrahy R C, Nayak B K,Banerjee K and Sarkar S K 2007 Anthropogenic impact onwater quality of Chilika lagoon RAMSAR site: A statisticalapproach; Wetlands Ecol. Manage. 15 113–126.

Ramasamy S M 2006 Remote sensing and active tectonics ofSouth India; Int. J. Rem. Sens. 27(20) 4397–4431.

Rao S G, Radhakrishna M and Murthy K S R 2015 Aseismotectonic study of the 21 May 2014 Bay of Bengalintraplate earthquake: Evidence of onshore–oAshore tec-tonic linkage and fracture zone reactivation in the northernBay of Bengal; Nat. Hazards 78 895–913.

Rhea S 1993 Geomorphic observations of rivers in the OregonCoast Range from a regional reconnaissance perspective;Geomorphology 6(2) 135–150.

Rockwell T K, Keller E A and Johnson D L 1984 Tectonicgeomorphology of alluvial fans and mountain fronts nearVentura, California; In: Tectonic Geomorphology (eds)Morisawa M and Hack T J, Publications in Geomorphol-ogy, State University of New York, Binghamton,pp. 183–207.

Roy S and Sahu A S 2015 Quaternary tectonic control onchannel morphology over sedimentary low land: A casestudy in the Ajay-Damodar interCuve of Eastern India;Geosci. Front. 6 927–946.

Silva P G, Goy J L, Zazo C and Bardajı T 2003 Fault-generated mountain fronts in southeast Spain: Geomorpho-logic assessment of tectonic and seismic activity; Geomor-phology 50 203–225.

Shimabukuro Y E and Smith J A 1991 The least-squaresmixing models to generate fraction images derived fromremote sensing multispectral data; IEEE Trans. Geosci.Remote Sens. 29 16–20.

Sohoni P S, Malik J N, Merh S S and Karanth R V 1999 Activetectonics astride Katrol Hill Zone, Kachchh, Western India;J. Geol. Soc. India 53 579–586.

Telford W M, Geldart L P and SheriA R E 1990 AppliedGeophysics (2nd edn), Cambridge University Press, 792p.

Vaidyanadhan R and Ghosh R N 1993 Quaternary of the eastcoast of India; Curr. Sci. 64 804–816.

Venkatarathnam K 1970 Formation of the barrier spit andother sand ridges near Chilka Lake on the east coast ofIndia; Marine Geol. 9 101–116.

Wells S G, Bullard T F, Menges C M, Drake P G, Karas P A,Kelson K I, Ritter J B and Wesling J R 1988 Regionalvariations in tectonic geomorphology along a segmentedconvergent plate boundary, PaciBc coast of Costa Rica;Geomorphology 1 239–265.

Zhou W, Wang S, Zhou Y and Troy A 2006 Mapping theconcentrations of total suspended matter in Lake Taihu,China, using Landsat-5 TM data; Int. J. Rem. Sens. 27(6)1177–1191.

Corresponding editor: NAVIN JUYAL


an integrated geomorphological and geophysical study of

Documents