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Tayebeh Kiani, Nadim Hydrad, Ghaforpur Anbaran Parastoo,
Volume 7, Issue 1 (5-2020)
Volume 7, Issue 1 (5-2020)
Abstract
Active tectonics of the Roudbar region:
with special reference to the landslides of the area
Tayebeh Kiani, Assistant Prof. in geomorphology, Kharazmi University
tayebeh.kiani@gmail.com
Hyrdad Nadim, MSc in environmental geology, geological hazards trends, Geological Survey & Mineral Exporation of Iran
hirad.nadim@gmail.com
Parastoo Ghaforpur Anbaran, PH.D Student in Geomorphology, Kharazmi University
parastooghaforpur@yahoo.com
Extended abstract:
Introduction: Due to its specific morphology and extensive tectonic activities, Roudbar rigion has always been affected by various geological hazards such as earthquakes, floods, biological pollution and landslides, which landslide is one of the most active phenomena in the region of this vast And mountainous area. Within the Roudbar geological sheet, 11 large and small landslides have been recorded with different yields and properties, some of which have catastrophic consequences, including the Roudbar and Fatalak landslides, which occurred as a result of the earthquake of June 31, 1990 Has caused devastating events in the Roudbar area and resulted in casualties and financial losses. Extreme performance of tectonic phases, which enact a major role in landslides, construction factors, road and rail, Steep slopes of topography, Sloping Loose Materials, are a various factors in the occurrence of such landslides. Due to the fact that landslide is predictive, preventive and sustainable, it is important to identify and zoning in the country and province and Perform basic geological studies in prone araes to landslides with a large scale. Due to the high potential of the region for the subsequent landslides and the properties of the intact areas with the old landslide areas, In present research, it is necessary to determine the most important factor in landslide occurrence in Roudbar area through field investigations and based on that, plan management will happen for controlling landslide phenomenon. Eventually, using geomorphic indices, the tectonic activity status of the Roudbar region is determined, and with the adaptation of the location of landslides and faults with the tectonic activity zones map, relationship between tectonic and landslide are investigated. Also, the risk zone, where there is a probability of landslide instability, is determined.
Method: The study area is located at 45 ° 36 'to 30 '45 ° 36' north latitude and 30 '22 ° 49' to 49 ° 49 'east longitude. Roudbar is one of the southern cities of Gilan province, which has a reputation for having olive gardens, and is named after its seasonal and permanent rivers. Roudbar city leads to from north to Rasht, south to Roudbar Alamut (from Qazvin province), from east to Lahijan and from west to Fomen city.
In the first phase, based on ground surveys and laboratory studies, the geological map in the scale of 1: 25,000 and other required data, limited area and Condition landslides are identified on aerial photos and satellite imagery. In the second phase of this research, geomorphic indicators the mountain front sinuosity index (Smf), the ratio of width to depth valley floor (Vf), Stream Length Index (SL), Basin Shape (Bs), Asymmetry Factor (AF) are used. Then, the results of the indicators are presented as a tectonic activity index (LAT).
Conclusion: Based on ground surveys and laboratory studies, the geological map in the scale of 1: 25000 and other required data, limited area and Condition landslides are identified on aerial photographs and satellite imagery. Based on this, it was found that Roudbar landslides were more affected by structural factors and weight (slope loading) has taken place. It seems Structural factors hidden in most of the landslides in the region. Based on the results of the tectonic activity relative index (Lat), most sub-basins have high and moderate tectonic activity. In term of width, the intense class includes with 195.55 square kilometers (67.21%) of the total area. The integration of different tectonic zones with the location of the landslide zones of the region, the close relationship between the zones with intense and moderate tectonic activity with the landslide zones designated in the first part of this study shows that the zones with Fatalak, Lavie, Roudbar, Filde landslides are in areas with intense tectonic activity and The landslides of Dashtgan, Talabar, Taklim, Nesfi, Dolatabad, Herzavil are located in the moderate tectonic activity zone. Based on ground surveys, the results of calculations of geomorphic indices indicate the relation between the activity of the land area and the landslide hazard. Considering the inevitability of the faults' activity and the resulting hazards, it is suggested that, in order to improve the country's substructure development, more detailed and larger scales on the landslide mechanism introduced in this research (Including determination of gradient safety factors (FS), calculation of the risk of slipping region and applying slope stability and safety methods, etc.), be done Systematicly and in coordination with organizations and related departments.
Keywords: Active tectonic, Geographic Information System, Geomorphic indices, Landslide, Roudbar.
Bibi Zahra Hosseini Giv, Sara Kiani, Syed Morovat Eftekhari, Mahdi Saghafi, Siros Esmaeili,
Volume 10, Issue 2 (9-2023)
Volume 10, Issue 2 (9-2023)
Abstract
Introduction
Today, in addition to exploiting environmental resources, humans must be able to recognize environmental hazards and try to reduce their damages. The location of Iran in the Alpine-Himalaya mountain belt has made Iran one of the high-risk seismic areas, and the east of Iran is no exception to this rule. The fault activities of eastern Iran, especially east and west of Lut, are a serious threat to the residents of eastern Iran. The activity of old and young faults and the emergence of new faults have provided the basis for the occurrence of destructive earthquakes in these areas. And it still continues and has been able to provide problems for the population living in the east of Iran.
The purpose of this research is to investigate the role of the Giv fault system in the occurrence of morphotectonic evidence and active tectonic analysis in the studied area, which has achieved favorable results according to the model used and the studied sources. The model used in this research, which is derived from similar examples in foreign sources, mostly deals with the destructive aspect of tectonics and has achieved the desired goals. Based on this, it should be seen if the morphotectonic evidence of the Giv fault system can be a sign of more activity and more threat in this part of the range (southern domain of Baghran mountains) or not? After studying various sources, the sources that answer the research questions were selected and further analyzed, and the conceptual model derived from these sources, which has a qualitative-analytical aspect, was used. Therefore, according to the main objectives of this research, which follows the destructive and instantaneous tectonic aspect, sources were selected that provided the most information to answer the research question, the sum of the information expressing the active tectonics in the studied area.
Research Methodology
The Giv fault system is a part of the Nehbandan-Kash fault in the east of the Lut block, and in the Giv plain, north-east of the Lut, with an almost west-east direction, it passes through the south of the Giv village and continues to Deh Mir and Karijgan in the west of the Giv plain. Giv village is located in Khosf County in South Khorasan province and in the center of Giv plain, south of Baghran Birjand Mountains and north of Shah Mountain.
The current research is of applied and developmental research type, and according to the history of seismicity of the region and historical data, it can be a step in the direction of knowing the seismic risk areas and also reminds the local residents to be more prepared. The conceptual model used in this research, which is derived from similar foreign examples, examines mostly the destructive aspect of tectonics.
In this research, the library work started by collecting and receiving a series of domestic and foreign sources, followed by the translation of foreign sources over a long period of time. Also, statistics and information were received from Geological Organization and Geophysics Institute, Birjand University, Birjand Seismological Center. Field studies, interviews, surveys and field measurements, using geological and topographic maps and satellite images, and using Google Earth and Arc GIS software, analysis and synthesis of information were carried out. Most of the data were used as qualitative data and to some extent quantitative data in the analysis.
Result and Discuction
The morphotectonic evidence in the studied area indicates a high risk of seismicity in the Giv fault pack, which is more dangerous than other parts of the Giv fault system.All the evidences such as uplift and cliffs in the south of Giv, significant change of the bridge river near the mouth and bed digging in this section show the uplift and activity of the South Giv fault and the travertine formation associated with the earthquake in the south of Giv, as well as the evidence of the growth of the Young Giv fold in 5 km. North of Giv village, such as the deviation of Pol and Minakhan rivers and excavation of the Minakhan river bed (Antecedence phenomenon), the presence of three generations of alluvial fans in the vicinity of the Young Giv fold, all indicate active tectonics and the rise of the Giv fold and the occurrence of destructive earthquakes. All the above-mentioned evidences are a serious alarm for the residents of Giv fault, especially Giv village, and require more study work, strengthening of villages, and proper planning for construction works so that the past tragic events of Giv village do not repeat in the future and this issue is taken into consideration in the discussion of land development.
Today, in addition to exploiting environmental resources, humans must be able to recognize environmental hazards and try to reduce their damages. The location of Iran in the Alpine-Himalaya mountain belt has made Iran one of the high-risk seismic areas, and the east of Iran is no exception to this rule. The fault activities of eastern Iran, especially east and west of Lut, are a serious threat to the residents of eastern Iran. The activity of old and young faults and the emergence of new faults have provided the basis for the occurrence of destructive earthquakes in these areas. And it still continues and has been able to provide problems for the population living in the east of Iran.
The purpose of this research is to investigate the role of the Giv fault system in the occurrence of morphotectonic evidence and active tectonic analysis in the studied area, which has achieved favorable results according to the model used and the studied sources. The model used in this research, which is derived from similar examples in foreign sources, mostly deals with the destructive aspect of tectonics and has achieved the desired goals. Based on this, it should be seen if the morphotectonic evidence of the Giv fault system can be a sign of more activity and more threat in this part of the range (southern domain of Baghran mountains) or not? After studying various sources, the sources that answer the research questions were selected and further analyzed, and the conceptual model derived from these sources, which has a qualitative-analytical aspect, was used. Therefore, according to the main objectives of this research, which follows the destructive and instantaneous tectonic aspect, sources were selected that provided the most information to answer the research question, the sum of the information expressing the active tectonics in the studied area.
Research Methodology
The Giv fault system is a part of the Nehbandan-Kash fault in the east of the Lut block, and in the Giv plain, north-east of the Lut, with an almost west-east direction, it passes through the south of the Giv village and continues to Deh Mir and Karijgan in the west of the Giv plain. Giv village is located in Khosf County in South Khorasan province and in the center of Giv plain, south of Baghran Birjand Mountains and north of Shah Mountain.
The current research is of applied and developmental research type, and according to the history of seismicity of the region and historical data, it can be a step in the direction of knowing the seismic risk areas and also reminds the local residents to be more prepared. The conceptual model used in this research, which is derived from similar foreign examples, examines mostly the destructive aspect of tectonics.
In this research, the library work started by collecting and receiving a series of domestic and foreign sources, followed by the translation of foreign sources over a long period of time. Also, statistics and information were received from Geological Organization and Geophysics Institute, Birjand University, Birjand Seismological Center. Field studies, interviews, surveys and field measurements, using geological and topographic maps and satellite images, and using Google Earth and Arc GIS software, analysis and synthesis of information were carried out. Most of the data were used as qualitative data and to some extent quantitative data in the analysis.
Result and Discuction
The morphotectonic evidence in the studied area indicates a high risk of seismicity in the Giv fault pack, which is more dangerous than other parts of the Giv fault system.All the evidences such as uplift and cliffs in the south of Giv, significant change of the bridge river near the mouth and bed digging in this section show the uplift and activity of the South Giv fault and the travertine formation associated with the earthquake in the south of Giv, as well as the evidence of the growth of the Young Giv fold in 5 km. North of Giv village, such as the deviation of Pol and Minakhan rivers and excavation of the Minakhan river bed (Antecedence phenomenon), the presence of three generations of alluvial fans in the vicinity of the Young Giv fold, all indicate active tectonics and the rise of the Giv fold and the occurrence of destructive earthquakes. All the above-mentioned evidences are a serious alarm for the residents of Giv fault, especially Giv village, and require more study work, strengthening of villages, and proper planning for construction works so that the past tragic events of Giv village do not repeat in the future and this issue is taken into consideration in the discussion of land development.
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