**2. Geological and geotechnical parameters in urban planning**

Geological and geotechnical investigations that include the details compatible to the planning scale before the planning and design of a city have an indispensible significance in the evaluation of suitability for settlement and land use decisions. The main stage of creating sustainable, durable and safe cities is to carry out natural structure analysis and synthesis by comprehensive investigations (geological, hydrological, engineering geology, geotechnic, seismicity, natural resource analysis etc.) and contemporary scientific methods (GIS, Multi Criteria Decision Analysis, Multi Criteria Decision Support Systems etc.).

Correlation Between Geology, Earthquake and Urban Planning 419

Fig. 1. An example of landslide in Daly City, California from USGS (US Geological Survey)

Fig. 2. An example of flooding in Borçka Town, Artvin, TURKEY. It is taken from http://www.t24.com.tr/haberdetay/54382.aspx. Photographer is unknown.

website. Photographer is unknown.

Geological investigations are the studies that aim to understand the statigraphic relation of rock and soils and tectonism of the settlement area. Besides, these field data provided by the investigations on the rock and soil of the urban area are to orient the upper scale plans (national and regional scale) and provide a base for detailed geotechnical studies.

Geological studies are the qualitative investigations that mostly cover scientific interpretation, definition and classification. These studies comprise of the tendencies and settlement of upper scale geological structure elements as tectonostratigraphic relations of formations, fault, folding, incompatibility and detailed scale geological structures as layer and of the investigation and the mapping of active fault lines. Geology maps, generally, are prepared in between the scales of 1/100000 and 1/25000 and in planning they serve as a base and guide for the regional and environment plans.

Hydrogeological t models in 1/25000 scale, too, are among the important inputs and natural threshold values of natural structure analyses before the planning. These hydrogeological studies orienting the sustainable planning in the synthesis conducted before the settlement can be listed as the location of aquifer constituting the groundwater, ground water level, direction of motion and its seasonal change, the determination of geological structures (anticlinal, synclinal, fault etc) that direct the ground water and its association with urban structures, surface waters in the areas desired to be opened to the settlement or in current settlements, the feeding and the discharge areas of ground water, natural drainage network detection and its mapping. These geological data, at the city and the basin scale, provide basis for the environment plans which are the planning stages of the settlement decisions. In environment plans, policies regarding spatial distribution of the population, decisions regarding the distribution of infrastructure and settlement units and policies for the reduction of earthquake hazards are developed.

Investigations that reveal the engineering properties of geological units in urban settlement areas are within the context of engineering geology studies. These include experimental studies in the field and laboratory medium rather than observational ones. These studies conducted in rock material and rock mass scale cover the determination of discontinuity properties of the rock masses (its location, number, spacings, discontinuity, infill situation, roughness, etc.) mass weathering degree and mass strength by experimental and emprical methods.

Engineering geology maps provide more detailed information about the soil that the city will rest on with quantitative data and it is an important guide to support the true decision mechanism in both habitability and land use. Generally, prepared in 1/5000 scale, these maps are fundamental basis for the master plans of the planing stage (similarly with 1/5000 scale and on which the macroform of the city is developed) where the decisions on usage such as densities, transportation systems, open green area arrangement, infrastructure, dwelling, commerce are made. When the geological unit in the ground in the urban and new settlement areas has the soil nature, index properties of the ground (grain size distribution, porosity, Atterberg limits etc) and engineering properties (cohesion, internal friction angle, natural unit volume network etc) are determined by in situ (investigation excavations and boring investigation) and laboratory experiments and calculation methods.

Besides, in the urban settlement area, unstable regions and areas that has geohazard (landslide (Figure 1), rock fall-overturn, flood (Figure 2), seismicity, liquifaction, settlingconsolidation, carstic cavitations (Figure 3) etc) are analized and their effects on urbanization are investigated.

Geological investigations are the studies that aim to understand the statigraphic relation of rock and soils and tectonism of the settlement area. Besides, these field data provided by the investigations on the rock and soil of the urban area are to orient the upper scale plans

Geological studies are the qualitative investigations that mostly cover scientific interpretation, definition and classification. These studies comprise of the tendencies and settlement of upper scale geological structure elements as tectonostratigraphic relations of formations, fault, folding, incompatibility and detailed scale geological structures as layer and of the investigation and the mapping of active fault lines. Geology maps, generally, are prepared in between the scales of 1/100000 and 1/25000 and in planning they serve as a

Hydrogeological t models in 1/25000 scale, too, are among the important inputs and natural threshold values of natural structure analyses before the planning. These hydrogeological studies orienting the sustainable planning in the synthesis conducted before the settlement can be listed as the location of aquifer constituting the groundwater, ground water level, direction of motion and its seasonal change, the determination of geological structures (anticlinal, synclinal, fault etc) that direct the ground water and its association with urban structures, surface waters in the areas desired to be opened to the settlement or in current settlements, the feeding and the discharge areas of ground water, natural drainage network detection and its mapping. These geological data, at the city and the basin scale, provide basis for the environment plans which are the planning stages of the settlement decisions. In environment plans, policies regarding spatial distribution of the population, decisions regarding the distribution of infrastructure and settlement units and policies for the

Investigations that reveal the engineering properties of geological units in urban settlement areas are within the context of engineering geology studies. These include experimental studies in the field and laboratory medium rather than observational ones. These studies conducted in rock material and rock mass scale cover the determination of discontinuity properties of the rock masses (its location, number, spacings, discontinuity, infill situation, roughness, etc.) mass weathering degree and mass strength by experimental and emprical

Engineering geology maps provide more detailed information about the soil that the city will rest on with quantitative data and it is an important guide to support the true decision mechanism in both habitability and land use. Generally, prepared in 1/5000 scale, these maps are fundamental basis for the master plans of the planing stage (similarly with 1/5000 scale and on which the macroform of the city is developed) where the decisions on usage such as densities, transportation systems, open green area arrangement, infrastructure, dwelling, commerce are made. When the geological unit in the ground in the urban and new settlement areas has the soil nature, index properties of the ground (grain size distribution, porosity, Atterberg limits etc) and engineering properties (cohesion, internal friction angle, natural unit volume network etc) are determined by in situ (investigation excavations and boring investigation) and laboratory

Besides, in the urban settlement area, unstable regions and areas that has geohazard (landslide (Figure 1), rock fall-overturn, flood (Figure 2), seismicity, liquifaction, settlingconsolidation, carstic cavitations (Figure 3) etc) are analized and their effects on

(national and regional scale) and provide a base for detailed geotechnical studies.

base and guide for the regional and environment plans.

reduction of earthquake hazards are developed.

experiments and calculation methods.

urbanization are investigated.

methods.

Fig. 1. An example of landslide in Daly City, California from USGS (US Geological Survey) website. Photographer is unknown.

Fig. 2. An example of flooding in Borçka Town, Artvin, TURKEY. It is taken from http://www.t24.com.tr/haberdetay/54382.aspx. Photographer is unknown.

Correlation Between Geology, Earthquake and Urban Planning 421

necessitated multiparametered tough decision process. Thus, this caused the development

Geological data within the planning discipline, before the planning, are evaluated in investigation, analysis and synthesis stages. These data with suitability to settlement analysis determine the development potential of the city by revealing the geologic threshold

Before the planning all geoenvironmental limiters, geohazards, geological-geotechnical data are evaluated as geologic thresholds. These natural geoenvironmental restrictions, besides the areas of natural hazard (earthquake, landslide, flood etc.), can be classified as cultivated areas and forest lands, water resources, reservations, geological sites etc. These natural thresholds are assessed with manmade thresholds as historical and archeological sites, mania plans, military zones and the habitability analysis are made including urban

Urban settlements have the tendency to develop with a varying pace depending on the policy of the urban development, economy, geographical features and geologic hazards. On the growth of the urban areas, there exist several natural structure thresholds as topography, soil condition, accessibility. Coping with these thresholds necessitates the analyses and syntheses that are developed by contemporary scientific methods. The selection of the methods of threshold analysis or habitability analysis is based on the number of criteria in the analysis, their quality, self values of the city and made by planners and project group (geological engineer, civil engineer, architect etc). In literature (Dai F. C.,et al.,. (2001), Darvishsefan A. A. et al.. (2004), Jabr, W.M. and El-Awar, F.A. (2004), Kolat Ç., et al.. 2006, Marinoni O. (2004), Marinoni O. (2005), Saaty T. L. (2008) ) there developed several mathematical and statistical methods analyzing based on the space to be used in settlement analysis and land use decisions. These methods (Threshold analysis technique, Spatial analysis via GIS, MCDA, MCDSS etc) beyond the sole natural structure analysis, provide the possibility of testing the habitability by correlating physical planning with economical, sociological and technological factors and by considering the current

Although the thresholds caused by restricting geological environment, depending on the extent of geohazard, sometimes can be overcome by technical precautions, the cost of technique can deadlock the habitability economically. Therefore, threshold analyses should realize the cost analyses of the alternatives besides providing the avoidance of urban risks

Therefore, the thresholds playing a role in the planning and development of a urban area can be divided into two groups as geoenvironmental thresholds and structural thresholds caused by the macroform of the city and structural features.The first group can be listed as topography, geological structure, hydrogeology, geosites and geoparks, ecology, climate, vegetation, geological properties of urban soil and excavatability, seismicity etc. On the other hand, the second group is the current land use of the city and its

These geoenvironmental thresholds affect the development and the settlement of the city in different ways. In some cases, these factors can be both advantage and disadvantage for the urban development. Although the hardness and the durability of the rocks in the settlement ground bring extra cost in excavatability, especially for creating earthquake resistant cities and soundness it is a necessary condition. Loose and swampy soils have features that can harm the structure in terms of load carrying capacity, settlement and

and be a guide in creating the sustainable and durable cities with minumum cost.

of scientific methods for spatial based analyses statistically and mathematically.

and restrictions.

parameters.

macroform of the city.

infrastructure system.

Fig. 3. An example of karstic space in Yucatan, Meksico. It is taken from http://www.hackturk.net/komplo-teorisi/287458/cukurlarla-ilgili-komplo-teorileri.html . Photographer is unknown.

In the cases where geological, hydrogeological and engineering geology studies are insufficient, more subscale maps (1/1000) are used. These studies covering geotechnical investigations, albeit not sufficient for urban design, provide valuable data as the plans showing the cadastre of urban equipment for master plan decisions, city blocks and layout, roads, slopes, bridges, squares, traditional textures. The data for the urban design in building scale are provided by more detailed geotechnical survey on the basis of parcel. On the basis of the parcel, geological-geotechnical investigations, depending on the geologic threshold and the extent of the hazard, can be worked on 1/2000, 1/1000 or 1/500 scale maps as well as on 1/250 scale depending on the extent of georisk within the context of building plot.

### **3. Earthquake as a planning threshold**

The turning point of the transition of the mankind from the rural life to the urban life is the industrial revolution in 19th century. Migration started after this revolution from the villages to the cities has brought several settlement problems along with it. The studies aimed to resolve these problems resulted in the emergence of the urban planning methods and their development. In paralel with the increasing city population, the need for new land for settlement started to increase. This demand of land increased the urban risks by urging to use of the lands unsuitable for settlement and in physical planning the site selection

Fig. 3. An example of karstic space in Yucatan, Meksico. It is taken from

Photographer is unknown.

**3. Earthquake as a planning threshold** 

building plot.

http://www.hackturk.net/komplo-teorisi/287458/cukurlarla-ilgili-komplo-teorileri.html .

In the cases where geological, hydrogeological and engineering geology studies are insufficient, more subscale maps (1/1000) are used. These studies covering geotechnical investigations, albeit not sufficient for urban design, provide valuable data as the plans showing the cadastre of urban equipment for master plan decisions, city blocks and layout, roads, slopes, bridges, squares, traditional textures. The data for the urban design in building scale are provided by more detailed geotechnical survey on the basis of parcel. On the basis of the parcel, geological-geotechnical investigations, depending on the geologic threshold and the extent of the hazard, can be worked on 1/2000, 1/1000 or 1/500 scale maps as well as on 1/250 scale depending on the extent of georisk within the context of

The turning point of the transition of the mankind from the rural life to the urban life is the industrial revolution in 19th century. Migration started after this revolution from the villages to the cities has brought several settlement problems along with it. The studies aimed to resolve these problems resulted in the emergence of the urban planning methods and their development. In paralel with the increasing city population, the need for new land for settlement started to increase. This demand of land increased the urban risks by urging to use of the lands unsuitable for settlement and in physical planning the site selection necessitated multiparametered tough decision process. Thus, this caused the development of scientific methods for spatial based analyses statistically and mathematically.

Geological data within the planning discipline, before the planning, are evaluated in investigation, analysis and synthesis stages. These data with suitability to settlement analysis determine the development potential of the city by revealing the geologic threshold and restrictions.

Before the planning all geoenvironmental limiters, geohazards, geological-geotechnical data are evaluated as geologic thresholds. These natural geoenvironmental restrictions, besides the areas of natural hazard (earthquake, landslide, flood etc.), can be classified as cultivated areas and forest lands, water resources, reservations, geological sites etc. These natural thresholds are assessed with manmade thresholds as historical and archeological sites, mania plans, military zones and the habitability analysis are made including urban parameters.

Urban settlements have the tendency to develop with a varying pace depending on the policy of the urban development, economy, geographical features and geologic hazards. On the growth of the urban areas, there exist several natural structure thresholds as topography, soil condition, accessibility. Coping with these thresholds necessitates the analyses and syntheses that are developed by contemporary scientific methods. The selection of the methods of threshold analysis or habitability analysis is based on the number of criteria in the analysis, their quality, self values of the city and made by planners and project group (geological engineer, civil engineer, architect etc). In literature (Dai F. C.,et al.,. (2001), Darvishsefan A. A. et al.. (2004), Jabr, W.M. and El-Awar, F.A. (2004), Kolat Ç., et al.. 2006, Marinoni O. (2004), Marinoni O. (2005), Saaty T. L. (2008) ) there developed several mathematical and statistical methods analyzing based on the space to be used in settlement analysis and land use decisions. These methods (Threshold analysis technique, Spatial analysis via GIS, MCDA, MCDSS etc) beyond the sole natural structure analysis, provide the possibility of testing the habitability by correlating physical planning with economical, sociological and technological factors and by considering the current macroform of the city.

Although the thresholds caused by restricting geological environment, depending on the extent of geohazard, sometimes can be overcome by technical precautions, the cost of technique can deadlock the habitability economically. Therefore, threshold analyses should realize the cost analyses of the alternatives besides providing the avoidance of urban risks and be a guide in creating the sustainable and durable cities with minumum cost.

Therefore, the thresholds playing a role in the planning and development of a urban area can be divided into two groups as geoenvironmental thresholds and structural thresholds caused by the macroform of the city and structural features.The first group can be listed as topography, geological structure, hydrogeology, geosites and geoparks, ecology, climate, vegetation, geological properties of urban soil and excavatability, seismicity etc. On the other hand, the second group is the current land use of the city and its infrastructure system.

These geoenvironmental thresholds affect the development and the settlement of the city in different ways. In some cases, these factors can be both advantage and disadvantage for the urban development. Although the hardness and the durability of the rocks in the settlement ground bring extra cost in excavatability, especially for creating earthquake resistant cities and soundness it is a necessary condition. Loose and swampy soils have features that can harm the structure in terms of load carrying capacity, settlement and

Correlation Between Geology, Earthquake and Urban Planning 423

In the settlements with earthquake risk, for the determination of urban risks geological data analysis is not sufficient alone. Building stock and quality in the urban area and the authentic nature of urban texture are also important factors in the evaluation of the earthquake effects. Therefore, while the urban risk analyses are conducted, all the parameters based on the current settlement quality and features, concentration, equipments,

Hazard mitigation studies before an earthquake is the most significant stage of disaster preparation process. In this process, the determination of the primary risks and the corresponding precautions for these risks decrease the life and monetory losses during an earthquake. The first step of the determination of the risks at urban areas is to understand the soil behavior that the city rests on by investigations. Besides, the identification of the building quality of the building stock and the revealing of the soil-structure interaction define the type and the approach of the precautions. New settlements are to be realized under the light of the geological data of the city. The inputs of geological data into the planning and design scale play an effective role in the reduction of urban risks. However, these data should be simple enough for planners and designers so that they are understood and implemented. The accurate use and the synthesis of those data banks are of prime importance in understanding the behavior of earthquakes on urban elements. These data providing inputs for architecture, planning and design shape the city. It is an indispensible necessity that in the creation process of earthquake resistant sustainable cities, geology, planning, architecture and design disciplines work together in a way developing a common

The risk level of the city changes with the population density, building quality, local ground conditions and distance to fault line. The city is subjected to one single earthquake magnitude and threat, however, settlement units that constitutes the city are faced to different levels of urban risks. The resistance of the settlements that have high quality and earthquake resistant buildings resting on hard soil to the same magnitude earthquake, certainly, will be higher than that of ordinarily constructed areas on problematic and loose soil conditions (Figure 4) due to their geotechnical properties. Therefore, the former will have less urban risks. In other words, in urban areas buildings are constructed with different materials in different structural systems and they can be newly constructed or already completed the economic life. Therefore, at the instant of the earthquake the reaction of the building and the extent of the damage will be controlled by the structural features and the

In earthquake prone areas, the effect of earthquake waves on the ground, how this effect is reflected to the building and the reaction of the building to this effect should be clarified in an accurate way by interdisciplinary work. These valuable data obtained by experimental analysis, synthesis and calculations help to the determination of the precautions against urban risks. These precautions can be as strengthening of the buildings or evacuation of weak buildings or abandoning of the settlement area before the earthquake during the stage of hazard mitigation as well as the providing of the transportation of the aids in emergency and constructions after earthquakes through a short and alternative routes and the

infrastructure and transportation networks should be included in the analyses.

**4. Urban earthquake risk** 

terminology.

geotechnical characteristics of the ground.

determination of the regions of emergency action.

consolidation problems. Land use decisions as the selection of multi-storey building, medium storey building, low rise building, open green areas and industrial use areas, when considered with ground properties, one area that is not suitable for one use do not necessarily have the risk for some other use. For instance, a swampy area that is not suitable for the construction of multistorey building can satisfy the requirement for open green area arrangement.

As for topographic threshold, with the increase of slope habitability and the cost increases. Rough topography urges the urban design, construction layout, building type and structuring requirements. While 15% of slope in settlement increases the cost, the slope over 30% results in serious technical infrastructure problems. On the other hand, the slope under 5% creates drainage problems.

In an urban area with earthquake hazard risk, earthquake analysis should have the priority and the directive role. The detail and the qualification of the analysis and synthesis before planning exhibit variability from upper scale studies to subscales ones. In urban settlements and development areas, the distance to the fault, the features of the ground, topographic factors, liquifaction requirements, landslides and floods as secondary threats, the ratio of fullness and emptiness, the selection of open green area should be analyzed. Structural order, structuring requirements should be arranged in a way that the effects of probable earthquake are prevented. In order not to have resonance, the interaction of soil and structure and the vibrational periods should be evaluated well. The selection of technology and material that control the building quality should be determined considering the soil condition and seismicity.

In urban design and settlement, prevailing wind direction and insolation are very important. In settlement pattern there should have air corridors to reach all buildings and buildings should be designed in a way that does not interrupt others's light. As for the site selection for the industry, similarly, prevailing wind direction is very important in the sense that spreading malodor to the city and air pollution. Besides, in rainy regions, the risk of flooding should be taken into account and flood risk analysis should be conducted. At the regions under risk, appropriate precautions (correcting the stream beds, leaving the stream beds for open space arrangements rather than opening those to the settlement) should be taken. Moreover, climate properties also affect the foundation type and depth regarding the settlement.

Ecological values are destroyed with the effects of urban development and the natural balance is degenerated. Therefore, in any kind of habitability analysis natural balance should be taken into consideration and the living habitats should be protected.

Urban development areas should be in relation with the current land use. The current transportation and infrastructure system, social equipment, commerce and important centers of the cities should be associated with new subcenter and settlement units. A settlement pattern disconnected from the current city will have difficulty in supplying the needs and developing.

Geoenvironmental and urban thresholds, after evaluated one by one and their priorities and the weights calculated by statistical methods (MCDA, MCDSS, GisVBA, AHP, Grey relation analyses etc.), are superposed with the maps showing natural and human activity thresholds and in final synthesis map the remaining areas out of the thresholds are defined as the urban development directions. Afterwards, the decisions on urban use areas (residential, commercial or industrial) are given in line with threshold analysis and cost analysis.
