علل وقوع و پيامدهاي ژئومورفولوژيك زمين لغزه 16 خردادماه 1384 محور اردبيل-تبريز در گردنه صايين (منطقه آذربايجان، غرب استان اردبيل)

The causes and geomorphologic consequences of landslide in 16.3.1384 in Ardabil- Tabrize road - saien defile (Azarbayjan area- west of Ardabil province)

A landslide occurred in 16.3.1384, in the way of Ardabil- Tabrize in Saien defile. One person died due to fall of his automobile and several machines damaged and more heavy damages occurred in the road. Effective factors to make this landslide were: gradient of the slope (more than 35 degree), spring rains some days before landslide occurrence (from the first day of Farvardin 1384 until sixteenth of Khordad 150mm rainfall occurred, that some of this rain infiltrated into the soil and increased liquefaction of soil. Intense weathering of earth surface materials (more than 5 meter depth), permeable and relatively thick soil (.5- 1.5 meter). In the surface of earth, excess of saturation capacity superficial formation (on the average 53 percent), surplus of plastic limit (26.30 percent) and liquid limit (34.92 percent) under surface formations such as: volcanic tuffs and other volcanic rocks that to make difficult infiltration of water in the depth of earth prepare the way for occurrence landslide. Along with the landslide, some of geomorphic phenomena occurred that we can present them such as: landslide escarpment, landslide cup, lake of landslide and etc. Reconstruction operations by Ardabil provinceʹs road and transportation office led to change in the geomorphologic landscape, and sometimes had led to morphogenesis. In this study, we will try to study the beneficial factors in landslide occurrence in 16.3.1384 and its geomorphic results.