207

Keywords: earthquake, Izmit, SPOT HRVIR data, VIS model

ABSTRACT: The aim of this study is to use remotely sensed data to record earthquake-inducedchange in urban areas. On 17 August 1999 at 3:02 a.m. local time, the Izmit earthquake occurredon the North Anatolian Fault Zone (NAFZ) in the northwest Turkey. The earthquake’s epicenter(near the town Golcuk) was located at latitude 41.8° and longitude 29.9° and the earthquake had adepth around 10 to 16 km. This earthquake caused considerable damage in the urban areas of Izmit,Adapazari, Golcuk and Yalova. In this study, SPOT HRVIR (XI and PAN) images obtained beforeand after the earthquake were used to detect earthquake induced damages in Adapazari. The pre-and post-earthquake images were geometrically corrected and classified separately. The imagedifference between 25 July 1999 and 4 October 1999 SPOT HRVIR Panchromatic image was usedto determine locations of collapsed buildings. Moreover, SPOT HRVIR images were used to formVegetation-Impervious-Soil (V-I-S) composition model in order to determine area of collapsedbuildings. The damage map obtained from Adapazari Metropolitan Municipality was comparedwith processed remotely sensed data. Earthquake induced damages in urban areas were interpretedusing the damage map, results of V-I-S model and difference image.

1 INTRODUCTION

Turkey is an earthquake country, and The North Anatolian Fault Zone (NAFZ) is one of the mostimportant active strike-slip faults in the World. The NAFZ, with a total length of 1500 km, is anactive fault (Sengor, 1979; Barka, 1992; Okay et al., 1999) that result from northward movementof African and Arabian plates (Alpar and Yaltirak, 2002). These plates cause the Anatolian block tobe extruded westward at an average rate of about 29 mmyr–1 (McClusky et al., 2000). The lastcentury, many buildings have been collapsed and many people have lost their lives as a result oftwenty-five earthquake with Moment Magnitudes (Mw) >6.5 (Barka and Nalbant, 1998; Kayaet al., 2004a).

On 17 August 1999, Kocaeli (Izmit) earthquake (Mw = 7.4) are the largest natural disasters ofthe 20th century in the Turkey after the 1939 Erzincan earthquake. Kocaeli earthquake had beenbroken about 140 km long western part of the 1500 km long NAFZ in a multiple rupture process(Toksöz et al., 1999.) Its epicentre is located (near the Izmit city) at 41.80° N and 29.9° E, the depthis at 16 km (Figure 1). The earthquake is affected some city centre such as Izmit, Adapazari, Yalova,Istanbul, Bolu, Bursa and Golcuk. However, Golcuk and Adapazari were affected more than theother city centre. The dead and injured totalled approximately 15,851 and 43,953 respectively incity centres (Sahin and Tari, 2000) and approximately 18,000 and 48,000 respectively in greaterurban areas (Barka, 1999).

Analyses of earthquake induced damage in urban areas by meansof remotely sensed data

S. Kaya, E. Saroglu & N. MusaogluITU, Geodesy and Photogrammetry Engineering Department,Remote Sensing Division 34469 Maslak Istanbul, Turkey

208 S. Kaya, E. Saroglu & N. Musaoglu

Remotely sensed data havebeen widely used for change detection analysis of short and longterm periods and determination of damages due to the natural disasters. Remote sensing technologycanbe used for the detection of land use/cover changes, forest fires, glacier movements, naturaldisaster monitoring, landslides, volcanoes and earthquakes. In a disaster case,damages should bedetermined immediately to conduct an efficient intervention process. It is disadvantageous to usefield survey data for mapping purposes in an emergency situation.

The objectives of this study are; (i) quantify the extents of heavy damaged and collapsedbuildings on 17 August 1999 earthquake in Adapazari using satellite image data, (ii) determine theland use changes trend, and (iii) define the accurate quantity and orientation of change trend forland use change in urban areas by means of V-I-S model.

2 THE STUDY AREA AND DATA

Adapazari inner city, the most heavily damaged city on 17 August 1999 earthquake, is selected asstudy arae (Figure 1). Adapazari was recontructed again after the earthquake on 22 June 1967.However, after 1980s new city was reconstructed in anunplanned manner inthe regions which were

Figure 1. Study area (A) Turkey map (B) general view of Adapazari city (C) pre-earthquake image ofAdapazari inner city (25 July 1999) (D) post-earthquake image of Adapazari inner city.

209Analyses of earthquake induced damage in urban areas by means of remotely sensed data

lake bed and agriculturallandformerly. In spite of the base problems, a lot of buildings wereconstructed as multiple storeys. The most important reason of having heavily damages in Adapazariis that buildings were constructed on readily-liquefied sediments (Scawthorn, 1999; Erken, 1999).During the earthquake, some buildings were not collapsed but they moved towards to right or leftand some buildings were sunk to ground because of ground liquefaction. Other causes of buildingdamage were:

• Poor concrete quality;• Poor reinforcement;• Weak storey within a multi-storey building (e.g. open space at the first floor);• Structurally unsuitable alterations (e.g. added floor);• Improper (unstable, corrupt, illegal) construction.

Figure 2. Ground photographs of 17 August 1999 earthquake damage.

3 IMAGE PROCESSING AND VIS MODEL

In order to ensure the integration of remotely sensed data with topographic maps and other ancillarydata, satellite images must be defined in same projection system. For this reason, satellite imagesmust rectified. In this study, SPOT HRVIR data were rectified into UTM projection using 1/25000scale topographic maps. Urban ecosystem canchange abruptly because of the damages caused bynatural disasters and impacts of people. Multitemporal rapidly processed satellite images can beused to determine these changes. Our reserach analyze the earthquake-induced changes in Adapazariusing remotely sensed data which were obtained in short time inteval. Derived data were evaluatedin Vegetation-Impervious-Soil model. The Vegetation-Impervious-Soil (V-I-S) of Ridd (1995) (Figure3) describes the biophysical composition of an urban area as a function of three components:vegetation, impervious (surfaces such as buildings and roads) and soil (defined as surfaces that areneither vegetation nor urban) (Madhavan et al., 2001; Phinn et al., 2002). This model shows theaccurate quantity and trend of land use changes in urban areas (Kaya et al., 2004b).

The pre-earthquake and post-earthquake images were classified using the Iterative Self-OrganizingDATA (ISODATA) classifier (without atmospheric correction). Twenty-five ISODATA spectralclasses were combined to form 4 classes: (i) vegetation, (ii) impervious I (urban), (iii) imperviousII (collapsed buildings) and (iv) soil (neither vegetation or urban).

Difference image can be obtained by subtracting two images obtained in different dates and thisimage can be used todeterminethe land use changes. The difference imege was obatained bysuntracting 25 July1999 SPOT HRVIR Panchromatic and 4 October 1999 SPOT HRVIR panchromatic

210 S. Kaya, E. Saroglu & N. Musaoglu

images. Rapidly changed areas were determined from this image by selecting the highest differencevalues. The areas represented with white colours illustrate the heavy damages and collapsed buildingsin inner city.

4 RESULTS AND CONCLUSIONS

Geometric structure of many objects changed as a result ıf earthquake, in Kocaeli (Figure 2). Thehomegenous structure in urban area turned into a heteregonous structure and roads destroyedbecause of the earthquake. Several buildings completely collapsed and geometric structure of mostof the buildings ruined (Figure 3). This situation caused an abrupt change in pixel values of postearthquake image data. Moreover, post earthquakeimage data introduced that there had beenhetergenous structure in Adapazari city center. Difference image obtained from pre and post earthquakedata is shown in Figure 4. The regions facing with abrupt land cover changes can be discriminatedfrom this image. According to census data taken from State Instute of Statistics, population ofAdapazari was 272 039 in 1990, 354 029 in 1997 and 340 825 in 2000 (http://www.die.gov.tr/nufus_sayimi/, 2003) (Table 1). Inner city population of Adapazari was 169 099 in 1990, 184 013in 1997; however, after the earthquake population deacreased to 172 000. After the earthquake,only 2629 citizens were officially reported as dead. Nevertheless, the change in population between1997 and 2000 is higher than this value. This means earthquake caused immigration especially ininner city of Adapazari. Adapazari is the most severely effected city from the earthquake when thecollapsed building number of other cities were examined (Table 1).

ISODATA classification results illustrated that 25.1% vegetation (forest, green areas etc.), 33.7%impervious (urban, road etc.) ve 41.2% soil (barren, agricultural land etc.) existed in Adapazaribefore the earthquake. Classification results of post earthquake data demonstrated that there was23.5% vegetation, 32.7% impervious and 43.8% soil area. 7.1% heavy damaged and collapsedbuildings were included to impervious class. Collapsed and heavy damage buildings have higher

Figure 3. Earthquake-induced damage map (a) general view of Adapazari (b) and (c) detail of city cente.

(a) (c)

(b)

Collapsed buildings

211Analyses of earthquake induced damage in urban areas by means of remotely sensed data

spectral reflectance than other impervious categories, so that they semmed in brighter tones (Kayaet al., 2005). There was not abrupt landcover changes in vegetation and soil categories. However,there had been a sudden change inland use of impervious class. An important problem for the studyregion was the trouble with quantifying the area of road class because general characteristics of thisclass was altered by the destruction of buildings. Area of heavy damaegs and collapsed buildingsare also including the area of some roads. The area of colapsed and heavy damaged buildings wereadded to soil class when forming the VIS model with post classification results. As a result, soilamount of VIS model was 50.9% for post earthquake data (Figure 5). Land use changevector wasfound using classification results of pre and post earthquake data. This vector shows the quantityand orientation of land use changes and is very important to determine the general characteristicsof urban areas.

ACKNOWLEDGEMENTS

We would like to thank the Istanbul Technical University Research Foundation (project number:30793) for support and Aykut Barka for the ground photographs.

Figure 4. Image differenced pre and post earthquake images.

Table 1. Number of buildings damaged in Adapazari, Izmit and Yalova by the 1999 earthquake(http://www.koeri.boun. edu.tr/depremmuh/extent.htm, 2003), and population of Adapazari within boththe greater urban area (http://www.die.gov.tr/nufus_sayimi/, 2003).

City Heavy damage Medium Light 1990 1997 2000to collapse damage damage population population population

Adapazari 11 373 5 815 8 763 272 039 354 029 340 825Izmit (Kocaeli) 3 614 12 944 13 335Yalova 9 637 8 988 12 677

212 S. Kaya, E. Saroglu & N. Musaoglu

REFERENCES

Alpar, B., and Yaltırak, C., 2002. Characteristic features of the North Anatolian Fault in the eastern Marmararegion and its tectonic evolution, Marine Geology, 190 329-350.

Barka, A., and Nalbant, S., 1997. 1700 ve sonrasi Marmara depremlerinin modellenmesi, Aktif TektonikArastirma Grubu 1. Toplantisi (ATAG-1), ITU Avrasya Yerbilimleri Enstitusu, Istanbul, Turkey, 32-40 (inTurkish).

Barka, A.A., 1992. The North Anatolian Fault Zone. Anales Tectonicae, Special Issue, 6, 164-195.Barka, A.A., 1999. The 17 August 1999 Izmit earthquake. Science, 285 1858-1859.Devlet Istatistik Enstitusu, 2000. Nufus sayimi sonuclari. Ankara, Turkey, http://www.die.gov.tr/nufus_sayimi,

20 May 2003.Erken, A., 1999. The effect of soil during Izmit earthquake. (http://1993.140.203.8/ earthquake /liq.htm, 01

July 2003).Kandilli Rasathanesi, 1999. http://www.koeri.boun.edu.tr/ depremmuh/extent.htm, 10 July 2003.Kaya, S., Muftuoglu, O., and Tuysuz, O., 2004a. Tracing the geometry of an active fault using remote sensing

and digital elevation model: Ganos segment, North Anatolian Fault zone, Turkey, International Journalof Remote Sensing, 19 3843- 3855.

Kaya, S., Llewellyn, G., and Curran, P.J., 2004b. Displaying Earthquake damage an urban area using aVegetation-Impervious-Soil Model and Remotely Sensed Data, International Archives of the Photogrammetry,Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7, Istanbul, 634- 638.

Kaya, S., Saroglu, E., and Musaoglu, N., 2005. Determination of the affects of earthquake induced heavydamages to city by means of remotely sensed data, TMMOB 10 Turkiye Harita Bilimsel Teknik Kurultayi,Ankara (in Turkish).

Madhavan, B.B., Kubo, S., Kurisaki, N., Sivakumar, N., 2001. Appraising the anatomy and spatial growth ofthe Bangkok metropolitan area using a vegetation-impervious- soil model through remote sensing,International Journal of Remote Sensing, 22 789-806.

Mcclusky, S.C., Balassanian, S., Barka, A.A., Demir, C., Ergintav, S., Georgiev, I., Gurkan, O., Hamburger,M., Hurst, K., Kahle, H., Kastens, L., Kekelidze, G., King, R.W., Kotzev, V., Lenk, O., Mahmoud, S.,Mishin, A., Nadariya, M., Ouzounis, A., Paradissis, D., Peter, Y., Prilepin, M., Reilinger, R., Sanli, I.,Seeger, H., Taeleb, A., Toksoz, M.N., and Veis, G., 2000. Global Positioning System constraints on platekinematics and dynamics in the eastern Mediterranean and Caucasus, Journal of Geophysics Research,105 5695-5719.

Okay, A.I., Demirbag, E., Kurt, H., Okay, N., and Kuscu, I., 1999. An active, deep marine strike-slip basinalong the North Anatolian fault in Turkey, Tectonics, 8 129-147.

Figure 5. Trend of VIS model from pre-earthquake to post-earthquake (from classified images result).

213Analyses of earthquake induced damage in urban areas by means of remotely sensed data

Phinn, S., Stanford, M., Scarth, P., Murray, A., Shyy, P.T., 2002. Monitoring the composition of urbanenvironments based on the vegetation-impervious surface-soil model by subpixel analysis techniques,International Journal of Remote Sensing, 23, 4131-4153.

Ridd, M.K., 1995. Exploring a V-I-S (Vegetation-Impervious-Soil) model for urban ecosystem analysisthrough remote sensing: comparative anatomy for cities. International Journal of Remote Sensing, 162165-2185.

Sahin, M., and Tari, E., 2000. The August 17 Kocaeli and the November 12 Duzce earthquakes in Turkey,Earth Planets Space, 52, 753-757.

Scawthorn, C., 1999, Kocaeli (Izmit) earthquake of 17 August 1999. Preliminary report, MultidisciplinaryCenter for Earthquake Engineering, State University of New York, http://mceer.buffalo.edu/research/turkeyeq/ScawPrelim.pdf, 10 July 2003.

Sengor, A.M.C., 1979. The North Anatolian transform fault: Its age, offset and tectonic significance, Journalof the Geological Society, 136 269-282.

Toksöz, M.N., Reilinger, R.E., Doll, C.G., Barka, A., and Yalcin, N., 1999. Izmit (Kocaeli) earthquake ofAugust 17, 1999: First report, Sismological Research Letters, 6 669-679.