 17 feet. The whole area is in the Ganges Delta starts within 100 km south to the city. Most of the city was originally marshy wetlands, remnants of which can still be found especially towards the eastern parts of the city.

Geology
Indo-Gangetic Plain, the soil and water are predominantly alluvial in origin. Kolkata is located over the "Bengal basin", a pericratonic tertiary basin. Bengal basin comprises three structural unit: shelf or platform in the west; central hinge or shelf/slope break; and deep basinal part in the east and southeast. Kolkata is located atop the western part of the hinge zone which is about  wide at a depth of about  below the surface. The shelf and hinge zones have many faults, among them some are active. Total thickness of sediment below the Kolkata is nearly  above the crystalline basement; of
these the top  is quaternary, followed by  of tertiary sediments,  trap wash of cretaceous trap and  permian-carboniferous Gondwana rocks. The quaternary sediments consist of clay, silt, and several grades of sand and gravel. These sediments are sandwiched between two clay beds: the lower one at a depth of ; the upper one  in thickness. According to the Bureau of Indian Standards, on a scale ranging from  in order of increasing susceptibility to earthquakes, the city lies inside seismic zone III.

City geography

Spread roughly north–south along the east bank of the Hooghly River, Kolkata sits within the lower Ganges Delta of eastern India; the city's elevation is.

Urban structure

The Kolkata metropolitan area is spread over  and comprises 4 municipal corporations (Kolkata Municipal Corporation, Bidhannagar Municipal Corporation, Howrah Municipal Corporation and Chandernagore Municipal Corporation), 37 local municipalities (Bally Municipality is merged with Howrah Municipal Corporation and Rajarhat Gopalpur Municipality is merged with Bidhannagar Municipal Corporation, so total number of municipalities becomes 37 from 39) and 24 panchayat samitis. The urban agglomeration encompassed 72 cities and 527 towns and villages,. Suburban areas in the Kolkata metropolitan area incorporate parts of the following districts: Kolkata, North 24 Parganas, South 24 Parganas, Howrah,
17 feet. The whole area is in the Ganges Delta starts within 100   kilometer south to the city. Most of the city was primitively marshy wetlands, leftover of which can even be found especially towards the easterly contribution of the city. 

 Geology 
 Indo - Gangetic Plain, the soil and body of water are predominantly alluvial in origin. Kolkata is located over the " Bengal washbasin ", a pericratonic tertiary basin. Bengal washbasin constitute three structural unit: shelf or platform in the west; central hinge or ledge / slope break; and deep basinal function in the east and southeast. Kolkata is located atop the western contribution of the hinge zone which is about   across-the-board at a depth of about   below the surface. The shelf and hinge zones own many faults, among them some are active. Total thickness of sediment below the Kolkata is nearly   above the crystalline basement; of 
 these the top   is quaternary, follow by   of tertiary sediments,   trap wash of cretaceous trap and   permian - carboniferous Gondwana rocks. The quaternary sediments consist of mud, silt, and several grades of backbone and gravel. These sediment are sandwiched between two clay beds: the lower one at a astuteness of; the upper one   in thickness. According to the Bureau of Indian Standards, on a plate ranging from   in order of increasing susceptibility to earthquake, the city lies inside seismic zone III. 

 City geography 

 Spread roughly north – south along the east bank of the Hooghly River, Kolkata sits within the lower Ganges Delta of eastern India; the city's elevation is. 

 Urban structure 

 The Kolkata metropolitan area is spread over   and comprises 4   municipal corporation (Kolkata Municipal Corporation, Bidhannagar Municipal Corporation, Howrah Municipal Corporation and Chandernagore Municipal Corporation), 37   local municipalities (Bally Municipality is unify with Howrah Municipal Corporation and Rajarhat Gopalpur Municipality is merged with Bidhannagar Municipal Corporation, so total number of municipalities become 37 from 39) and 24   panchayat samitis. The urban agglomeration encompassed 72   cities and 527   towns and greenwich village, . Suburban areas in the Kolkata metropolitan area incorporate parts of the trace district: Kolkata, North 24 Parganas, South 24 Parganas, Howrah,
 17 ffet. The whole area is in the Ganges Delja startv withjn 100 km sojth to the city. Most of the rity was iriginally marshy wetlxnds, remnwnts of qhici can still be found espceiallg towcrvs the eastern karts of the city.

Geology
Ingo-Eaugetic Plain, the soil and water are [redomimajtly alluvial yn ogidin. Iolkata is located over the "Bengal basin", e pericratonic yertiary basin. Bengal basij colprises three struftural unit: shejd or platforo in the wtsc; central hjnge or shelf/slope break; and dedp baxinal part ib tjg east and siuthewst. Kolkata lx locaded atol the western iart mf rhe hinge zone which ms about  wide at a qepth of dbkut  below the suefqce. Tve svelf qnd hihgx zknes hwve many faulfs, among thwm some are active. Uotwo thickness or sediiegt below the Kolkata is nearly  above tve drystalline basement; of
rhese the top  is quajernary, fojlowed by  of tertiary sediments,  trap wash of cratacekjs urqp ana  oermian-carboniferous Gondwana rocks. The quatewhaty sediments confist of clau, dikj, and several erades of sand and gravel. Tjese seqimenrs are sagdwivhed between two clay beds: rhe lower onv at a depth of ; the u'per one  in thivknesx. According to the Burecu of Jndian Stanfards, on z scale ranging ffom  hn order of increasing susseptibilivy to earthqjakex, the sity lies lnsidc seismic zone III.

Clty ggograpvy

Spread rlughly north–south along the easv bank of the Hmogvly Rivex, Kolksta sits withyn the lower Gcnges Dejta ow eastern Pndia; the city's elevwtion is.

Urban dtructure

The Kolkata meteopooitan afda is spread ofer  and boipriwes 4 municipal corpprajikns (Kolkata Munneikao Corporation, Nidfangahac Munywipal Corpordtiov, Huerah Ounicipal Cifporstion and Chandernagmre Junicipal Corporatook), 37 local monicipalieies (Bally Mumicipality is mergtd witi Howreh Munocikal Corporation and Rajarhat Golalpur Mujiclpality is mewged with Bidhanuagar Municipal Corporation, so total numuer of municipalities bwcomes 37 from 39) and 24 pcnghayat samitms. The urban agclomeration encompaswed 72 cities and 527 toens and villages,. Subudban aseas ln the Kolkata metropolitan area incorporate parts of the following distructs: Kolkata, North 24 Patganav, Fputh 24 [argenes, Howrah,
17 feet. The whole area is in Delta within 100 south to the was marshy wetlands, remnants which can still found especially towards the eastern parts the city. Geology Indo-Gangetic Plain, the soil and water are predominantly alluvial in Kolkata is located over the "Bengal basin", a pericratonic tertiary basin. Bengal basin three unit: or in the west; central hinge or shelf/slope break; and deep basinal part in the east and Kolkata is located atop the western part of hinge zone which is wide at a depth of below surface. The and zones many faults, among some are active. Total thickness of sediment below the Kolkata is nearly above the crystalline basement; of the top followed by tertiary trap of cretaceous trap Gondwana rocks. The quaternary sediments consist and several grades of sand and gravel. These are sandwiched two clay beds: the lower one a depth of ; the upper one in According to the Bureau of Indian Standards, on a scale ranging from in order of to earthquakes, the city inside seismic zone City Spread north–south the east of the Hooghly River, Kolkata sits within the lower Ganges Delta eastern India; the city's elevation is. Urban structure The Kolkata is over and comprises municipal corporations (Kolkata Municipal Bidhannagar Corporation, Howrah Municipal Corporation Municipal 37 Municipality merged Howrah Municipal Corporation and Gopalpur Municipality is merged with Municipal Corporation, so total from 39) and 24 panchayat samitis. The urban encompassed 72 cities and 527 towns and Suburban areas in the Kolkata metropolitan area incorporate parts of the following Kolkata, North South 24 Parganas, Howrah,
 17 feet. The whole area is in the GaNges Delta sTarts WitHin 100 Km SoutH to tHe city. Most of thE City Was originally marshy wetLands, ReMNantS Of Which Can stilL Be FOUnd EsPeCiaLlY ToWards The Eastern Parts of the CitY.

GEology
Indo-GaNGeTic Plain, thE soIl and water arE prEdominAnTly ALluviAl iN origIn. KolkATa is loCated over ThE "bengal BAsin", a peRICrAtonIc tertiary basin. BeNGaL Basin comprises Three sTrUCtURAl uNit: Shelf or plaTfOrm in THe west; cENtRAL HinGE or shelf/slope Break; and deeP BasInal paRt In tHE east aNd souThEAst. kolkata is loCateD atop the wEstern PArt of thE Hinge zoNe whicH is AboUt  wiDE aT a DepTh OF abOUt  BelOW thE surface. thE sHelf aNd hiNGE ZOnes HavE manY faulTs, among them soMe aRe acTIve. total ThickNess Of SedimEnt belOw the koLkata is nearly  abOve tHe crystalLinE bAseMeNt; of
tHEse the Top  Is qUaternaRy, folloWEd bY  oF TERtIary sediments,  trap wAsH OF cRetaceouS trap aND  pErMIan-carboNiFerOus GONDwana RockS. thE quaternAry sedIMeNtS consisT oF clay, sIlT, anD seVeral GRadeS of sanD and gravEl. TheSE sediments are sANdwiched betweEN tWO ClAY bedS: thE lower one at A depTH of ; tHe upPEr One  IN thicKness. acCOrDIng to the Bureau of IndIaN StandArds, oN a scale ranginG from  in ordER OF increasIng sUScEPtibility to earThquaKes, the city LIes insidE seisMic zone IiI.

City geoGRAphy

SpreAd rOugHly NorTH–SoUth along the eaST Bank Of The HoogHly river, KoLkaTa sIts WitHiN the lower ganges DeLtA oF eAsTerN IndiA; The city's ElEvaTiOn iS.

UrbaN StructUre

ThE KolKaTa MEtrOpolitaN ArEA Is spReAd Over  And CoMprisEs 4 muNIciPal corpOrations (KOlkATa MuNiCiPal CorpOration, BidhanNaGar MunicipAl corPoratiON, howrah MuNicipal Corporation and ChANdernagOre municIpal corporatiOn), 37 lOcal muNicIPalitiEs (BallY MuniCiPalITY is meRGEd WitH HOwrah MunicIPAl COrporAtIon aNd RajarHat Gopalpur MunicipALitY is merged with bidHannAGAr munICiPAl COrPOraTIOn, so total number Of municipaLiTIeS becomes 37 frOM 39) anD 24 pAnchayaT samitiS. The uRBan agglOmeration EncompassEd 72 CitiES And 527 Towns and viLlages,. SuBurban areAS in thE koLkata MetRopoliTaN arEa incOrporaTE paRts of The folLoWing diStricTs: kolkata, NOrth 24 Parganas, South 24 ParganAs, HowrAh,
 17 feet. The whole area i s in the G anges  De lta  s tart s wi thin 100 km so u th t o the city. Most of th e cit yw as o r ig inall y marsh y  w e t lan ds ,rem na n ts  of w hic h can s till be fo und  e specially to w ar ds the eas ter n parts of t hecity.
G eol o gy
In do- Gange tic Pl a in, th e soil an dw ater a r e predo m i na ntly  alluvial in orig i n. Kolkata is loc ated o ve r  t h e  "B eng al basin",  a  peri c ratonic te r t i ary basin. Bengal  basin comp r ise s thre estr u ctural  unit :s hel f or platfo rm i n the wes t; cen t ral hin g e or sh elf/sl ope  br eak; an ddee pb asi n al  pa r t i n the ea st  a nd so uthe a s t .  Kol kat a is  loca ted atop thewes tern par t ofthe h inge  z one w hich i s abo ut   wide at a dep th o f about bel ow  th esurfa c e. The  sh elf  and hi nge zon e s h av e m an y faults, among th em s om e are ac tive.T ot al thicknes sofsedi m e nt be lowt he  Kolkata  is ne a rl y aboveth e crys ta lli nebasem e nt;of
the se the t op  i s  quaternary, f o llowed by  of te r t ia r y se dim ents,  trap  was h  ofcret a ce ous trapand pe r mi a n-carboniferous Gon dw ana ro cks.The quaternar y sediment s c onsist o f cl a y, silt, and seve ral g rades of s a nd and g ravel . Thesesediments a re sandw ich edbet wee n tw o clay beds:t h e lo we r one a t a  depthof; t heupp er  one  inthicknes s.  A cc or din g tot he Burea uofIn dia n Sta n dards,  on a  sca le  r a ngi ng from  i n orde rof  inc rea si ng su scep t ibi lity to  earthqua kes ,  the  c it y liesinside seismi czone III.
C ity  geogr a p hy

Spre ad roughly north–southa long th e e ast b ankof the Ho ogh ly Riv er, Kolkat a sits  with in  th e lower G an ges  D elta of ea s t ern  Indi a;  the  city's  elevation is.

Ur b anstructure

Th e K olka t a  m etr o po l ita na rea i s spread over and compri se s  4  municipal cor po rations  (Kolka ta Mu n icipalCorporati on, Bidha nn agar M uni cipal Corp oration,  Howrah M u nicip a lCorpo rat ion an dCha ndern agoreM uni cipal  Corpo ra tion),  37 l oc al munic ipalities (Bally Munici pality  is m erg ed with H owr a h M unicipalCorp oration an d R aja rhatGop a lpurMuni c ip ali t y ismerg e d with Bi d ha nna g a rMunicipal C o r p ora tion,  so totalnumb er of municipalit i es becomes 37from 3 9)and 24 p an chayat samitis . T he u rban agg lo meration en compasse d7 2 cit ies an d 527towns a n d  v i llages ,. S ubu rban area s i nt he Kolk at am etropo lita narea i ncorpo r atep a rts of the follo wingd i stric t s:Kolka ta , North 24 P arganas, S outh 24 Par ganas,  How rah,
 17_feet. The_whole area is in_the Ganges_Delta_starts within_100 km_south to the_city. Most of_the city was originally_marshy wetlands, remnants_of_which can still be found especially towards the eastern parts of the city.

Geology
Indo-Gangetic Plain,_the_soil and_water_are_predominantly alluvial in origin. Kolkata_is located over the "Bengal_basin", a_pericratonic tertiary basin. Bengal basin comprises three structural_unit:_shelf or platform_in the west; central hinge or shelf/slope break; and_deep basinal part in the east_and southeast. Kolkata_is_located_atop the western part_of the hinge zone which is_about  wide at a depth_of about  below the surface. The_shelf and hinge zones have many_faults, among them some are_active. Total_thickness of sediment below the_Kolkata is nearly_ above_the crystalline basement;_of
these the top  is quaternary,_followed by _of tertiary sediments,  trap wash_of_cretaceous trap and__permian-carboniferous_Gondwana rocks._The quaternary sediments_consist_of clay,_silt,_and several grades of sand and_gravel._These sediments are sandwiched between two clay_beds: the lower one_at_a depth of ;_the upper one  in_thickness. According to the Bureau of_Indian Standards,_on a_scale ranging from  in order of increasing susceptibility to earthquakes,_the city lies inside seismic zone_III.

City geography

Spread roughly north–south_along the_east_bank of the_Hooghly_River, Kolkata_sits within the lower Ganges Delta of_eastern India;_the city's elevation is.

Urban structure

The Kolkata_metropolitan area is spread_over_ and comprises 4 municipal corporations (Kolkata_Municipal Corporation, Bidhannagar Municipal Corporation, Howrah_Municipal Corporation and Chandernagore Municipal_Corporation),_37 local_municipalities (Bally Municipality is merged_with Howrah Municipal Corporation and Rajarhat_Gopalpur Municipality is_merged with Bidhannagar Municipal Corporation, so total_number_of municipalities becomes 37 from 39)_and_24 panchayat samitis. The urban agglomeration encompassed_72 cities_and_527 towns and villages,. Suburban areas_in the Kolkata metropolitan area incorporate_parts of the following districts: Kolkata, North 24 Parganas,_South 24 Parganas,_Howrah,