Hazard Evaluation for Landslide Akiyuki Kawasaki, Doctoral Student Graduate School of Engineering, Yokohama National University, Japan

Where is Yokohama?

Background ・ Concentrated heavy rain strikes Japan every year ・ Many houses and buildings are damaged and lives are lost in the landslide and debris flow. ⇒ There are two major problems. ・ However, Existing policy is not enough. ⇒ Good policy is needed.

1. Problems in Policy “Hazard zone for landslide” is specified by Municipal government. It is Not applied for the these areas (In case of Yokohama), ・ less than 5 houses ・ the construction for landslide prevention was done

February 17, 1999 Minami Ward, Yokohama.

2. Problems in Governmental Organization ・ Bureaus, Departments, and Divisions of government hardly have a cooperation, even if same municipality. ・ They hardly share their data, because their purpose is different.

Purpose Purpose ・ Make Collaboration

Joint Research This study is a Joint Research between ・ City of Yokohama Bureau of building Bureau of road Bureau of disaster front office ・ Yokohama National University Tohoku University (Landslide) Tokyo Institute of Technology (Geology)

Purpose Purpose ・ Propose a new method “how to create a hazard evaluation for landslide in urban area from the Viewpoint as “a Planner”. ・ Utilize “Existing Data”. ・ Make Collaboration

Data

25 M DEM

横浜国立大学

(1966 ～ 1999)

Relationship Between Collapse and Slope

Calculated Angle (Degree) Number of Collapses / ha Number of Collapses per 1 ha & 1 degree of Calculated Angle Calculated Angle (Degree) Total Collapse Case (%) Ratio of total Collapses per 1 Degree of Calculated Angle (1966 ～ 1999)

⇒ Actual Angle ≑ ２．５ × Calculated Angle

Factor of Collapse

Type 1 Loam Mud Stone Type 2 Mud Stone Face Soil Type 3 Three Major Types of Geological Section in Yokohama Patterns of Geology Patterns of Geology

＋ Records of Collapse Specified Hazard Zone (Prefectural & Municipal) Type 1 Type 2 Type 3 Slump Fall Patterns of Geology Patterns of Collapse

Hazardous Evaluation for the Risk of Landslide

A B

-Distance from cliff -Density of buildings -Structures of buildings -Building use For example, Hospital, Welfare Facilities, etc Consider surrounding environments, as a potential evaluation of suffering form landslide Further Evaluation

See you next year! Akiyuki Kawasaki Graduate School of Engineering, Yokohama National University, Japan URL:

Yes No Yes No Yes No

The problems “Hazard zone for landslide” specified by local government. It is not applied for the these areas, ・ less than 5 houses ・ Apartment ・ The area where the construction for landslide prevention was done

⇒ Actual Angle ≑ ２．５ × Calculated Angle

- Propose to Create a New Methodology from the Viewpoint as a “ Planner ”. - Collaborative Project Between Prefectural and Municipal Government and Universities. Summery

Hazard Evaluation for Landslide Akiyuki Kawasaki, Doctoral Student Graduate School of Engineering, Yokohama National University, Japan