ABSTRACT

Azerbaijan area (NW Iran) is a region of intense deformation on seismicity, situated between two thrust belts of the Caucasus to the north and the Zagros Mountain to the South.

Landslides are the consequence of diverse and complex processes that probably affect every country that has topographic relief. In Azerbaijan, development of landslides hazard areas is occurring at a greater rate than In previous years. The region under survey is located in a slope mountain called; "Shorbayer" its slope is about 30 to 40 percent.

September 2, 2008 and previous earthquakes cause a vast number of phenomena such as landslide and rock- falls along the southern slope of Harzard- Oryantapeh mountain and many of rural homes suffred of heavy damages.

The direct effect of the catastrophic April 1981 and especially September 2, 2008 heavy earthquake and meteorological event was the reactivation of a large ancient rockslide, which affects the middle- lower part of Oryantapeh- Harzard Southern Slope. The slide involves a massive dacitic and volcanic rock mass the overall surface approximately is: V = 1/3πab. H = 1/3 π. 1500. 750. 100 = 1178. 106 m3

1 INTRODUCTION

Large Landslides affect mountain valley in Iran. They are characterized by a low probability of evolution into a catastrophic event but can have very large direct and indirect impacts on man, Infrastructures and the environment.

Recognition and identification of the types of landslides goes back at least 186 B.C. In China (Li, 1989), but systematic Identification and mapping of all landslide types in specific areas have developed mainly during the past few decades.

The areas on the southern Slopes of the So- called "Harzand- Dagh" in the northern part of " Oryantapeh" is affected by numerous mass movements. The So- called Harzand- Dagh landslide Involves an area of about 15 km2 and reaches a depth of over several meters and affects a 1800 m high slope, from a altitude of 2610 m at the ridge crest down to 1500 m at the valley bottom.

The morphological and structural characteristics of the are suggest subdividing in into three adjacent sectors, roughly corresponding to the villages older Harzand (Dash- Harzand) and north part Oryantapeh.

These sectors reflect, respectively, final, early and intermediate stages of the evolution of a site subject to a deep seated gravitational process.

The central sector, around "Kaha To Hassan- Baghi", "effects an early stage in the deformation process" it is clearly separated from the Harzand and Oryantapeh by a N- S striking scarp a few hundred meters long and 150- 200 m high.

The bedrock is this sector is more damaged in the middle and lower parts.

The western sector is called Riva Valley, which spreads through the Cretaceous hard limestone.

Riva Valley as a tectonic valley elongated approximately in a west- east direction with vertical walls is considered as a boundary between the clay stone and Neogene marl sediment and volcanic rocks of Pliocene- Quaternary periodicity age.

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