سنجش ارتباط طول گسل، بزرگي زمين لرزه، پهنه گسيختگي و جابجايي عمودي زمين (مطالعه موردي: دشت سيلاخور)

Earthquake statistical analysis for evaluate interact between fault length, magnetite, deformation and displacement (A case study Silakhor plane west Iran)

اين مقاله بر آن است تا خطر گسلش ناشي از زمين‌لرزه در دشت سيلاخور را به كمك سنجش پارامترهاي موثر (طول گسل، بزرگاي زمين‌لرزه، پهناي گسيختگي و جابه‌جايي عمودي) مورد بررسي قرار داده پهنه‌بندي مناسبي از ميزان خطرپذيري ناشي از آن را به عمل آورد. در اين پژوهش با استفاده از شواهد مربوط به اين پارمترها گسيختگي در پهنه‌هاي لرزشي از رخدادهاي قبلي تعيين و به كمك تكنيك‌هاي تحليل آماري تحديد شد. نتايج نشان مي‌دهد كه از مجموع گسل‌هاي موجود در اين دشت شش گسل توان بالقوه ايجاد زمين‌لرزه‌هايي با بزرگا و دامنه‌اي بين 8/5 تا بيش از 7 ريشتر دارند كه بنا بر همين روابط زمين لرزه‌هاي با اين بزرگا مي‌توانند در پهنه‌اي به وسعت 1 تا 3 كيلومتري پيرامون گسل، گسيختگي‌هايي ايجاد كنند كه ارتفاع مقادير جابه‌جايي عمودي آن‌ها به بيش از 107 سانتيمتر خواهد رسيد. شاخص‌هاي فوق مبناي پهنه‌بندي نواحي در معرض خطر گسلش قرار گرفته است. يافته‌ها نشان مي‌دهد كه شهر درود و 53 روستا از 163 روستاي محدوده مورد مطالعه روي پهنه‌هاي پر خطر گسلش، 22 روستا بر روي پهنه‌هاي با خطر متوسط گسلش و 37 روستا بر روي پهنه‌هاي كم خطر گسلش قرار دارند.

Building and infrastructure construction at ground surface or under the ground are required to consider the existence of faults to prevent the damages due to earthquake evidence. Furthermore, faults identification and recognition their shake and vibratory behavior will be an importance task to understanding and prediction the vulnerability in area. The main aims and goal of this study is to examine the risk of fault due to the earthquake in the Silakhor plan by the examination of effective parameters (fault length, magnitude, rupture radiance and vertical replacement). The tectonic condition as well as earthquake potential of area was examined at the first stage. To determine this condition, the historical earthquakes of the area were extracted from various seismological data resources such as USGS, IIEES etc. The earthquake vulnerability of area was extract and analyzed to identify the high potential zone along the known faults where the probability earthquake epicenter can be taken place along it .According to these factors, the ruptures and land deformation area due to previous earthquake events has been mapped and reanalysis based on statistical techniques. The results show out of all fault line where traverse in this area, 6 faults have a potential to induce earthquakes shake with magnitude in rage of 5.8 to 7. Which is the earthquake with average magnitude of 7.01 Richter can produce by Durod Fault as Varkooh Fault can produce the earthquake with average magnitude of 6.2 Richter, the remain known faults in area are able to produce earthquake with average magnitude of below the 6 Richter, The result also define that, such earthquakes can displace area along the fault ruptures with 107cm in vertical and 1 to 3 km² as land deformation domain. These results were modified as factors input for vulnerability assessment and earthquake hazard zonation. Furthermore, the study area was divided to in 3 zones (low, moderate and high hazard areas). Superimposing the earthquake hazard zonation map and digital settlement and infrastructures maps of area over the GIS environment shows out of 163 villages in study area the 53 villages located in high hazard zone, 22 villages in moderate hazard zone and 37 villages in a low hazard zone. Furthermore, the parts of two main roads (Khoramabad- Borujerd and Borujerd- Dorud) involved in high hazard zonation. Which is can cause lots of problems for assessing the area by blocking the main roads and make a double disaster in a earthquake events.