INTRODUCTION. Climate

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Harry Johnson
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2 INTRODUCTION Climate Landslides are serious natural disasters in many parts of the world. Since the past 30 years, rainfall triggered landslides and debris flows had been one of the natural disasters of the country. The best estimate of direct and indirect costs of landslide damage range between million baht.

INTRODUCTION Geology of Thailand 5 main geomorphology areas of Thailand are; 1) the central plain; the large alluvial flood plain and colluvium fans on mountain foots.

3 INTRODUCTION Geology of Thailand 5 main geomorphology areas of Thailand are; 1) the central plain; the large alluvial flood plain and colluvium fans on mountain foots. 2) the eastern coasts of low mountain range and coastal deposit. 3) the northeastern part; the high plateau of sandstone, siltstone and shale. 4) the northern and western continental highlands, the high mountain ranges formed by granitic rocks, metamorphic rocks, and old alluvium in the valley. 5) the southern part; the granitic mountain ranges on the west side combined with old and young sedimentation on the central and east sides of the peninsular.

4 INTRODUCTION During the last 30 years, the landslide cases were fairly well recorded. Landslide events in Thailand (GERD, 2006)

5 STUDY AREA High potential of landslide due to its geographic and geologic condition. High consequences for tourist After tsunami, developer tend to disturb the stable slope in the upper level

6 STUDY AREA This table shows some event of landslide records gathered by Patong municipality, it shows that most of the landslide has triggered by excessive rainfall.

7 Kalim Village Na Nai Village Landslide Events on October,

$Granite rock is found to be in moderately to highly weathered condition with various sets of joint and fracture.$

8 GEOLOGICAL CHARACTERISTICS Geological characteristics of Patong include formation of granite in Cretaceous Era and modern beach sediments in Quaternary period. Granite rock is found to be in moderately to highly weathered condition with various sets of joint and fracture. Left lateral strike-slip fault has found mostly with their strike lies between north-east to south-west direction.

9 GEOLOGICAL CHARACTERISTICS

LANDSLIDE SUSCEPTIBILITY MAP The landslide hazard area is determined using

Factor of safety against sliding and slope angle relationship is calculated

Other factors are also considered after extensive review of the latest

In determining the numerical rating for landslide potential of each 6

10 LANDSLIDE SUSCEPTIBILITY MAP The landslide hazard area is determined using weighing factor method. Factor of safety against sliding and slope angle relationship is calculated based on shear strength data. Other factors are also considered after extensive review of the latest literatures and after acquired more information in the target area. In determining the numerical rating for landslide potential of each 6 parameters, an area of 25 square meters grid cell has been employed for the analysis by GIS program. The weight-rating value of each parameter is determined in each square grid cell of each derivative map. Suttisuk et al., 2010

11 LANDSLIDE SUSCEPTIBILITY MAP The results of the analysis are shown in Figure. It clearly that the actual events are matched with the moderate to high landslide susceptibility area from the result of analysis with the matching of 78.2 percent. Suttisuk et al., 2010

12 Early Warning & Evacuation Action Critical Rainfall

13 Hazard Mapping and Evacuation planning Main road Hotel 2. Official place 3. Nanai village and hospital 4. Resorts and Spa 5. Temple 6. Police Station

Hazard Mapping and Evacuation planning Main road EOC 4 5 2 3 6 EOC 1 Shelter 1. Hotel 2.

14 Hazard Mapping and Evacuation planning Main road EOC EOC 1 Shelter 1. Hotel 2. Official place 3. Nanai village and hospital 4. Resorts and Spa 5. Temple 6. Police Station

15 CONCLUSIONS 1. Landslide Mapping is necessary to understand the factors that affect the occurrence of landslides. In the case of this study. Slope and the fault is a major factor landslides in the area. 2. The disasters in the past and the cause of the disaster, as well as rainfall is very important to analyze the management of landslide hazards. 3. The near real time landslide warning required extensive type of data such as the geotechnical properties of residual soil, geologic conditions and the rainfall data. 4. However, the field monitoring shall be performed to verify the analysis before the public warning can be issued.

EIT-Japan Symposium 2011 on Human Security Engineering

EIT-Japan Symposium 2011 on Human Security Engineering 2011 Disastrous Landslides at Khao Panom, Krabi, Thailand Suttisak Soralump Geotechnical Engineering Research and Development Center (GERD) Faculty