بررسی ارتباط شاخص‌های ریخت زمین ساختی با شتاب زمین‌لرزه در پهنه‌های گسلي ايندس،ايپک، آوج و کوشک نصرت(شمال باختر ساوه)
محورهای موضوعی :
بهار رضایی نهال
1
(دانشگاه آزاد اسلامی واحد تهران شمال)
محسن پورکرمانی
2
(دانشگاه آزاد واحد تهران شمال)
مهدی زارع
3
(پژوهشگاه بین‌المللی زلزله‌شناسی و مهندسی زلزله)
مريم ده بزرگي
4
(دانشگاه خوارزمي)
رضا نوزعيم
5
(دانشگاه تهران)
کلید واژه: ايران مركزي , تكتونيك فعال, شاخص‌های مورفومتري, گسل کوشک نصرت, گسل ایندس , گسل آوج , گسل ایپک. ,
چکیده مقاله :
گستره شمال غرب شهرستان ساوه در پهنه گسلي ایندس ، کوشک نصرت ، آوج و ایپک قرار دارد. گسل‌های ایندس ، کوشک نصرت ، آوج و ایپک از گسل¬هاي مهـم ايران مركزي به شمار می‌روند و در كواترنري نيز فعال می‌باشند . آخرين حركـات ايـن گسل‌ها را بـه عهد حاضر نسبت داده‌اند، بنابراين برآورد شـاخص‌هـاي مورفـومتري به‌منظور شناسـايي تـأثير تكتونيك فعال آن بر تكامل تكتونيكي حوضه‌های زهكشي ضروري به نظـر می‌رسد. لـذا در ايـن مطالعه به تجزیه‌وتحلیل شش شاخص مورفوتكتونيكي مهم نظير گراديان طولي رودخانه، نبود تقـارن حوضه زهكشي، انتگرال هيپسومتريك، شكل حوضه زهكشي، نسبت عـرض كـف بـه ارتفـاع دره و پيشاني كوهستان پرداخته شده است. براي تشكيل حوضه‌ها بر روي پهنه موردمطالعه از نرم‌افزار ) Arc Hydroاز افزونه‌های نرم‌افزار (Arc GIS بر پايه داده‌های حاصل از مدل رقـومي ارتفـاعي استفاده شده است، سپس شش شاخص مورفوتكتونيكي بر روي هر يك از حوضه‌ها موردمحاسـبه و رده‌بندی قرارگرفته است. درنهايت، شاخص تكتونيك فعال) (Iatمحاسبه گرديده كه بر اساس آن پهنه به چهار رده فعاليت تكتونيكي بسيار بالا، بالا، متوسط و پـايين رده‌بندی گرديـده اسـت. بـر اساس شاخص IAT ، پنج درصد از محدوده موردمطالعه، فعاليت تكتونيكي بسـيار بـالا نشـان می‌دهند، 25درصد از پهنه موردمطالعه فعاليت تكتونيكي بالا، 65 درصد فعاليت تكتونيكي متوسط و حدود پنج درصد هم فعاليت تكتونيكي پايين را نشان می‌دهند. در گستره مطالعاتي بيشترين سطح فعاليت تكتونيكي در بخش شمال شرق پهنه می‌باشد. در اکثر بخش‌ها میزان سطح فعاليت بالا و متوسط می‌باشد و مرتبط با فعالیت گسل‌های کوشک نصرت ، ایپک ، آوج در نظر گرفته شده است.
The northwest zone of Saveh city is located in the Indes, Kooshk e Nosrat, Avaj, and Aipak fault zones. Indes, Kooshk e Nosrat, Avaj, and Aipak faults are considered the major faults in central Iran, which are also active in the Quaternary, and their last movements are attributed to the present time. Therefore, the estimation of morphometry to identify the effect of active tectonics on the tectonic evolution of drainage basins seems necessary. In this study, six important morphotectonic indices were analyzed including the longitudinal gradient of the river, asymmetry of the drainage basin, hypsometric integral, drainage basin shape, the ratio of the floor width to the valley height, and mountain front. To model the formation of basins in the studied area, Arc Hydro software (Arc GIS add-ins) was used based on data derived from a digital elevation model. Then, 6 morphotectonic indices were compiled and classified on each of the basins. Finally, the Active Tectonic Index (IAT) was calculated, according to which the study area was classified into 4 categories including very high, high, intermediate, and low tectonic activity. According to the IAT index, 5% of the study area shows very high tectonic activity, 25% of the studied area has high tectonic activity, 65% of it has average tectonic activity and about 5% of the tectonic activity is low. Moreover, seismic acceleration was prepared to confirm the result of morphological indices in the estimation and analysis of active tectonics in the region. In this study, the highest level of tectonic activity can be seen in the north-eastern part of the area. In most sectors, the level of activity is high and intermediate, which is related to the activity of Kooshk-e-Nosrat, Aipak, and Avaj faults.
نبوی، م. ح.، 1355 ، دیباچه ای بر زمین شناسی ایران ، 109 .
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