INTRODUCTION

A) Turkey is found in Northern Hemisphere , it is in 26⁰ – 45⁰ Eastern Meridians , 36⁰ - 42⁰ Northern Parallels . It’s neighbors are Greece , Bulgaria , Georgia , Armenia , Iran , Iraq and Syria . Position of Turkey cause some geologic hazards . The most important one is earthquake . Turkey found in “ Mediterranean – Himalayan System “  along the this line especially Turkey and Greece have frequently and violent earthquakes that have shallow focus around the Turkey . Turkey was faced with many earthquakes during  its history , just it had more than 40 earthquakes in republican era and these earthquakes caused more than 100.000 people deaths . Moreover Turkey has 96 % earthquake risk and  it’s 98 % of population are under the risk . On the other hand Turkey’s 98% of industrial services have risk and it’s 92% of dams are on the earthquake zones . There are three zones in Turkey these are North Anatolian Fault (NAF) , Aegean Graben System (AGS) , and East Anatolian Fault (EAF) and these zone have big seismic activities . Regime of pressing is dominant in the east to depend on it  load and reverse faults found in there , on the other hand  depend on effective attraction tension normal faults occur in west . NAF is the most dangerous zone for Turkey . It starts from the  Karlıova ( Mus ) and go on to Erzincan , Tosya , Gerede , Bolu , Duzce , Adapazarı and Izmit , finally it arrive to Sea of Marmara . It’s lengthiness is 1600 km in east to west and it covers 50 km areas around it’s north and south . Some of the big earthquakes on this zone are 1939-1992 Erzincan earthquake , 1942 Niksar - Erbaga earthquake , 1943 Tosya – Ladik eaarthquake , 1944 Bolu – Gerede earthquake , 1951 Kursunlu – Ilgaz earthquake , 1957 Abant – Bolu earthquake , 1966 Varto earthquake , 1967 Adapazarı earthquake , 1971 Bingol earthquake 1999 Izmit – Golcuk earthquake and 1999 Duzce earthquake . In the years of  1999 occurred 2 earthquakes , these were Kocaeli – Golcuk earthquake and Duzce earthquake , first  earthquake occurred in Golcuk  at 03:02 a.m to continue 50 seconds , its magnitude was 7.4 and intensity of it was XI , in the this earthquake  15000 people died , 32000 people injured , 50000 buildings were collapsed , second earthquake occurred in Duzce at 18:57 to continue 30 seconds , its magnitude was 7.1 and intensity of it was X (maximum) , in the this earthquake 800 people died , 5000 people injured , 5883 buildings were collapsed .

B) Golcuk is a town of kocaeli in northern turkey along the izmit gulf of the sea of marmara , it is a small place but it is very important for the navy and industrial services which have a large base in there therefore it is relatively well developed . It  is in 28⁰ 30’ - 31⁰ east longitude and 40⁰ 30’ - 41⁰ 30’ north latitude , and it found on NAF can be seen between Sapanca Lake and Gulf of Izmit and general way of it is N80E – N80W and EW . It’s lengthiness is 60 km between Sapanca and Golcuk . Fault creates new part between Sapanca – Golcuk segment and Golcuk – Karamursel segment, this new part caused to slide of coast in to the gulf during the 1999 earthquake . This fault is parallel to Golcuk-Karamursel coast line , it lie to sea from there and general way of this fault is N80-85E .

 During the  earthquake , along the gulf of Izmit coast all buildings collapsed  because of landslide and weak ground , on the other hand any buildings didn’t collapse along the high lands ,   also section – spreading that is type of liquefaction occurred in Golcuk  , and  Tupras Gas Filling Establishment was fired by earthquake because Tupras found on filled ground . Also water ,telephone,  swear  and electricity  services were broken , there was some disasters occurred like cholera etc ,  roads , bridges were broken to cause difficulty of transportation so food supply , shelter , technical and medical helps   didn’t provide exactly .

C ) Golcuk is under a big risk because the city is built on NAF and Golcuk will continue to be affected by the earthquakes because of the NAF and geological structure therefore the location of  town’s residential area relative to the geology is very important for  safety planning . There are mainly two types of geologic structures in Golcuk ; alluvium and aslanbey formation . The alluvium area is old quaternary that is in cenozoic era , in this period Northwest Europe and America were covered by glaciers and sea level degreased , in this period  in middle latitude glaciers that found on top of mountains melted because of high temperature depends on it sea level increased also many lakes occurred even tropical region’s basins. Alluvium area was created by stream selimiye . It is mainly composed of clay , silt , fine sand with organic clay and pebbles with the alluvium is between 1 and 15 m thick in east of the coast . Total thickness of it is between 1 to 50 m but it increase towards to east . Aslanbey formation is old pliocene that is in tertiary  period  . In this epoch 50% of animals and vegetation covers   occurred  , generally humid climate was occurred in this epoch and lakes were dominant , also world had almost today’s shape , especially movements of increase occurred along the orogenic system and subsidence movements occurred in some places . Aslanbey formation  is exposed at d-130 roadway , hill of gozlemen , 1 march martyrdom , anafartalar street , and all high lands . The aslanbey formation is formed of siltstone , sandstone and clay stone , it has irregular structure but some layers of it is regular . It’s thickness is more than 100 m at Golcuk but it’s thickness increase between Sapanca Lake and Yalova , it’s minimum thickness is 700 m in that place . There are two types faults in Golcuk active and no active . The active fault starts at Kavaklı , which is near the coast , so this region is strongly affected by earthquakes . The southern part of Golcuk is less prove to earthquake damages than Kavaklı because of it’s  bedrock geology . In the 1999 earthquake many buildings near the coast in Golcuk collapsed while the high lands of Golcuk were less affected

D )  Regions which are on the aslanbey formation is near the surface are strong and 4 stories buildings can be built in there . Regions are on aslanbey formation have %25 topographic slope , these regions are composed of clay and silt , so have landslide risk and these regions should be drain aged    , and 3 or 4 stories are suitable for these regions . In aslanbey formation some regions are around river valley and flood plain , so flooding events can be seen 3 or 4 stories are suitable with permission . In these regions aslanbey formation has some thickness or alluvium formation is weak , so in these regions some preventions should be supplied for settlement and 3 stories buildings can be built . Regions which are on alluvium zone that is thick , clay , silt , and pebble is in it , are mixed with ground water , so some preventions and special ground systems should be applied for these regions  and 2 stories are suitable . Regions that are in alluvium zone which has organic clay and silt  , so special ground systems must be used for these regions  , 1or 2 stories are suitable . These regions are on alluvium zone but they are artificial filled regions so buildings foundations must be on the alluvium and 2 stories are proper . Region is in alluvium zone  on the kavaklı fault that  oblique to NAF  , yavuz street arrive to gulf that is parallel to kavaklı fault , this region found in there and it is not proper for settlement . Regions that are on the filled place , parallel to d-130 roadway should be parks or recreational area .

E ) Earthquake affected so much  population too in Golcuk , it caused to death , migration etc . Also amount of population density , increase and urban population rate degreased . Golcuk lost 18,4 % of population and golcuk’ s  population amount degreased from 11,2 % to 8,9 % . Urban population was 76,855 at 1997 but it is 55,790 at 2000 , moreover  rural population degreased too  , it was 55,080 at 1997 and  51,724 at 2000 . According to them total  population degrease is 24,320 between 1997 and 2000 . Proportion of  urban population was 58% at 1997 , and it is 51,8 % at 2000  , but proportion of rural population increase , it was 41,8% at 1997 , it is 48,2% at 2000 .

Population increase rate  was 24,1%o between 1990 and 1997 but it degreased to -67,6 between 1997 and 2000 . It was too much in urban population increase that was -105.8 it was 22,5%o  before the earthquake so urban population lost 21.065 people  , in rural it was -8,6 .it was 26,4%o before the earthquake so rural population lost 3356 people . People in per km was 662 people at 1997 , it was 520 people at 2000 . 33% of people died in golcuk that has 57% rate of death in kocaeli region , and 53% rate of injured people in kocaeli region too . 0-Every  1 person died per 4 people lived in golcuk according to earthquake area in Turkey , 10,3 % of families lost their relatives , and 1 person died per 25 people . 0-14 age group population was 19,182 at 1990 , and it formed 30% of urban population , it was 12,961 at 2000 , it formed 23% of urban population , the lost of this age group is 6221 people .

House people number was 18,000 before the earthquake , but it is now 6540 people in golcuk . 64% of population were lost because of death and migration . Every 1 person of 8,5 % of houses  migrated . Every 1 person 43% of family , 2 people 23% of family , 3 people 13% of family migrated . Anybody of 23%of family didn’t migrated . 14% of  people migrated to Istanbul and % 24 of people migrated to marmara region , % 19 of people migrated to black sea region and %17 of people migrated  to southeastern anatolian region .

F ) After the earthquake goverment built new houses for people , these houses settled on high lands of golcuk these region found on aslanbey formation , this place the most suitable region in golcuk , it found south part of golcuk .

G ) My  hypothesis is  settlement and population change after the earthquke becsause old residental area’s geological structures are not so proper for settlement because of it new settlement built more proper region in golcuk . My research question is  new reisdential area ‘s geology really well or not ?