Study of hazards induced by the Ahar-Varzegan Earthquake in Sarand chai Basin and its Surrounding

Abstract

An earthquake, generally considered being the most destructive and frightening of all forces of nature is a sudden rapid shaking of the earth caused by the breaking and shifting of rock beneath the earth’s surface. More casualties and financial losses due to secondary effects of the earthquake and after they occur. Iran is seismically active country and frequent and destructive earthquakes reveal the fact in different parts of the country. For example, two severe earthquakes happened on Sunday 21 Mordad 1391 in areas of East Azerbaijan province. Earthquake magnitude were 6/4 and 6/3 on the Richter scale near the Varzeghan and Ahar. The epicenter of both quakes was at a depth of 10 kilometers underground. The earthquake strongly shook towns of Ahar, Haris, and Varzeghan. It created a lot of casualties and financial losses. This study tries to draw a map of seismicity in the Sarand Chai and around the area, using seismic data to Tehran University Geophysics Agency, satellite imagery review the evidence and Frequent field observations whit use Arc/GIS. Finally, It is zoning the risk of landslides in the area in the event of an earthquake with the strength of 6.4 on the Richter scale. The results of this study show, the hazard of the earthquake in Ahar - Varzeghan include shaking, the type of landslides (slides, rock falls, debris flows…), ground rupture, liquefaction, groundwater level fluctuations and etc., based on field observations of the region. The zonation map show, that in the event of an earthquake with a strength of 6.4 on the Richter scale, will be 7% of the area in the very high hazard zone, 35 % in the high hazard zone and 7 % of the area in the low hazard zone, in terms of landslides occurrence.

Keywords

• hazards induced earthquake
• landslide
• ground rupture
• liquefaction
• ahar–varzeghan earthquake
• sarand chai basin