رفتارشناسی فضایی – زمانی فعالیت مجدد زمین‌لغزش قدیمی روستای حسین‌آباد کالپوش

لغزش های قدیمی یکی از عوامل شکست دامنه ها و وقوع لغزش های جدید در جهان هستند که با فعالیت مجدد خود، تهدید بزرگی را برای زندگی بشر، زیرساخت ها و سازه های مسکونی در مناطق شهری و روستایی به وجود می آورند. در این پژوهش، فعالیت لغزش قدیمی روستای حسین‌آباد در شمال استان سمنان، با استفاده از تصاویر سنتینل 1 و تکنیک تداخل سنجی راداری psi در بازه زمانی 2018-2020 ارزیابی شد. سپس با استفاده از مشاهدات میدانی، ارزیابی آسیب‌پذیری ساختمان ها (bva) و ارتباط مکانی آسیب آن‌ها با ژئومورفولوژی لغزش، رفتار فضایی- زمانی فعالیت لغزش قدیمی، مورد تحلیل قرار گرفت. نتایج تکنیک psi نشان می دهد میانگین نرخ جابه جایی به ترتیب در مدار صعودی و نزولی 19-12- و 16-22- میلی‌متر در سال است. این لغزش در تابستان حرکت خود را آغاز نموده و در دوره پربارش باران با 35- میلی‌متر بیشترین نشست را در بدنه اصلی و پای لغزش تجربه کرده است. مشاهدات الگوی ترک و ارزیابی آسیب‌پذیری ساختمان ها نیز نتایج تداخل سنجی راداری را تایید می نماید. بیش از 70 درصد ساختمان ها به دلیل بالاآمدگی و نشست خاک در بدنه اصلی و پای لغزش تخریب شده اند. همچنین در پنجه لغزش و مرزهای جانبی خسارت کمتری به ساختمان ها وارد شده است. این امر نشان از افزایش تغییرات در داخل توده اصلی لغزش قدیمی و حرکت مجدد آن به‌صورت لغزش چرخشی در دوره پربارش سال 2019 دارد.

spatial-temporal behavior of the reactivation of the paleolandslide in hossein abad village, kalpush, northeast of iran

introduction landslides are natural hazards in mountainous regions that cause significant damage to man-made structures, such as buildings, roads, and power transmission lines. complex geological, geomorphological, and climatic conditions lead to slope failures, where paleo landslides, formed during the quaternary period, stabilize over time. these historical landslides often reactivate due to triggers such as earthquakes, heavy rainfall, river erosion, changes in reservoir water levels (rwl), road construction, and deforestation. additionally, anthropogenic factors, such as construction within the landslide mass or agricultural activities on the crown of the landslide, can further destabilize these areas. the threat to human life and infrastructure is especially high when cities and villages are located on or near old landslides. examples of this can be seen in the vajont dam disaster in italy and the three gorges dam in china.in iran, especially in the alborz and zagros mountain ranges, numerous ancient landslides exist that reactivate under the influence of earthquakes, heavy rainfall, and human activities. assessing the vulnerability of buildings to such phenomena is critical. various methods, including insar radar interferometry and permanent scatterer interferometry (psi), are employed to monitor slow-moving landslides and evaluate their impact on structures. this study, integrating geomorphological data, landslide kinematics, and building vulnerability assessment, focuses on the reactivation of the hossein abad landslide in northern iran and analyzes its spatial-temporal behavior.material and methods hossein abad village, located in the kalpush district of miyami county in semnan province, is the largest village in the region. situated on moderate slopes and atop four old landslide terrains with an average slope of 14%, the village has expanded over time. this study was conducted in four stages, involving the collection, production, processing, and interpretation of historical, field, and radar remote sensing data.initially, a landslide geomorphological map of the active old landslides in hossein abad was produced using aerial photos, geological maps, and uav images. then, the radar interferometry technique was applied to analyze the kinematics of the landslide movement, with displacement rate maps generated from sentinel-1a/b radar data. subsequently, the vulnerability of buildings in the village was assessed through field visits and questionnaires, and a vulnerability map was produced using the classification method proposed by palmisano et al., 2016. damage to buildings was classified based on various indicators such as material type, structural characteristics, and crack patterns. the study also analyzed the spatial relationship between landslide movement and building vulnerability, focusing on the geomorphological context of the landslides.results and discussion in the village of hossein abad, four old landslides were identified, and over time, the development of the village and construction activities mainly expanded on the southern slope, directly over two large, old landslides. in 2013, the hossein abad earthen dam was constructed near these landslides, with a capacity of approximately 16 million cubic meters of water. heavy snowfall and rainfall in late 2018 activated these landslides, causing significant damage, including the collapse of more than 160 buildings. the main landslide, covering 22 hectares, exhibited rotational and compound movement over a marl-limestone bedrock.