Quantitative Landslide Risk Assessment between Mersin and Erdemli Region (Southern Turkey)

  I

7

INTERNATIONAL SYMPOSIUM ON

EASTERN MEDITERRANEAN GEOLOGY

18-22 October 2010

University of Çukurova ADANA - TURKEY

ABSTRACT BOOK

7th _{INTERNATIONAL SYMPOSIUM ON EASTERN MEDITERRANEAN GEOLOGY, 18‐22 October 2010 – University of Çukurova ADANA ‐ TURKEY} 

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QUANTITATIVE LANDSLIDE RISK ASSESSMENT BETWEEN MERSIN

AND ERDEMLI REGION (SOUTHERN TURKEY)

Tolga ÇAN (1)_{, Tamer Y. DUMAN} (2)_{, Engin ÇIL} (1)_{, Tolga MAZMAN} (1)

(1)_{Çukurova University, Department of Geological Engineering, TR-01330, Adana, TURKEY}

(2)_{General Directorate of Mineral Research and Exploration (MTA), Department of Geological Research, Earth Dynamics}

Research and Assessment Division TR-06520, Ankara, TURKEY

Landslide risk is defined as the expected number of lives lost, persons injured, damage to property or disruption of economic activity due to a particular landslide hazard for a specified time period within a given area. In this study, quantitative landslide risk maps were prepared, between Mersin and Erdemli region extending for 1600km2, considering landslide hazard, vulnerability and economic value of elements at risk. 1285 and 338 residences were either collapsed or heavily damaged in Mersin city, due to the landslides triggered by excessive rainfall in 1968 and 2001, respectively.

In order to determine the spatial probability of landslide occurrence, susceptibility maps were prepared for particular time periods using statistical relationships between landslides and landslide conditioning factors. Temporal probability of landslides was determined by considering the triggering factors from rainfall – frequency relationships. The exceedance probability of landslides occurrence in 5, 10, 25, 50 and 100 years time intervals were calculated. The probabilities of landslide size (extent) were obtained from frequency – size distribution of multi-temporal landslide inventory maps prepared after interpretation of four sets of aerial photographs. Then, landslide hazard maps for different landslide sizes (>0.1km2 and >0.01 km2), that will occur having exceedance probabilities for 5, 10, 25, 50 and 100 years periods were obtained. The elements at risk were considered only for roads (2916km), houses (13780) and agriculture lands (169 km2). Vulnerability was assessed by comparing losses with the actual economic value of the elements at risk and simply expressed as 1 for roads and houses, and 0.6 for agriculture lands.

Landslide risk maps were prepared by multiplying landslide hazard, vulnerability and actual economic values of elements at risk. The results indicate that the total expected economic losses for 50-year period of landslide sizes greater than 0.01 km2 and 0.1 km2 is about 243 million $ (%23 of total economic value) and 50 million $ (%5.5 of total economic value), respectively. It is suggested that the

risk maps produced by this study would help to perform effective landslide risk mitigation strategies of the region.