سناریوهای خطرپذیری زمین‌لرزه در مناطق شهری (مورد‌پژوهی: شهر اردبیل)

نوع مقاله : مقاله پژوهشی

نویسنده

گروه جغرافیا، واحد اردبیل، دانشگاه آزاد اسلامی،اردبیل، ایران

چکیده

مقدمه: ارزیابی خطرپذیری لرزه­ای در مقیاس شهری یک فعالیت ضروری برای ارزیابی پیامدهای بالقوه زمین­لرزه­های بزرگ است. این روش متشکل از یک سری مراحل پژوهشی سیستماتیک است که با شناسایی خطر لرزه­ای آغاز ­شده و با ارزیابی آسیب­پذیری ساختمان­ها ادامه می­یابد. تأثیر سناریوهای لرزه­ای بر روی ساکنین شهر اردبیل، هدف نهایی این مطالعه است تا ضمن فراهم ­ساختن اطلاعات کارآمد در مورد ارزیابی آسیب­پذیری لرزه­ای برنامه عملیاتی شهری به ­روز رسانی گردد.
مواد و روش­ها: در این تحقیق از روشی مبتنی بر شاخص آسیب­پذیری برای ارزیابی خسارت مورد انتظار در اردبیل استفاده شده است. این روش یک شاخص آسیب­پذیری را برای نمایش و تعیین اینکه آیا یک ساختمان به طبقه آسیب­پذیری خاص تعلق دارد، معرفی می­کند. این روش از میانگین توابع آسیب­پذیری نیمه تجربی استفاده می­کند که برای یک شاخص آسیب­پذیری معین به با لرزه­خیزی و خسارت مورد انتظار کاملا مرتبط است. تحلیل خطرپذیری برای سناریوهای لرزه­ای تعریف شده با شدت­های لرزه­ای V، V-VI، VI،VI-VII  و VII برای طراحی طرح­های اضطراری لرزه­ای انجام شده است.
نتایج و بحث: آسیب­پذیری بالا باعث آسیب فیزیکی مستقیم قابل توجهی به ساختمان­ها می­شود، حتی برای زمین­لرزه­های با شدت کم. در نتیجه خسارت فیزیکی مورد انتظار در صورت وقوع زمین­لرزه­های متوسط قابل توجه است. برای زمین­لرزه­ای با بزرگی V، انتظار نمی­رود خسارت قابل توجهی باشد، اما برای سناریوی با بزرگی VII، هر پنج منطقه و بافت­های فرسوده درون آن­ها سطحی از آسیب را تجربه خواهند کرد که اندکی بیشتر است. در بین مناطق پنج­گانه شهری، منطقه 2 به دلیل تراکم ارتفاعی بیشترین تاثیر اقتصادی را خواهد داشت و برای سناریوی با شدت VII حدود 261 میلیارد ریال هزینه خواهد داشت. تاثیر اقتصادی زمین­لرزه­ای برای مناطق پنج گانه از 101 میلیارد ریال برای زمین­لرزه­ای با بزرگای V-VI تا 844 برای زمین­لرزه­ای با بزرگای 7 است. با توجه به تاثیر یک بحران لرزه­ای، حجم قابل توجهی از تولید آوار وجود دارد. همچنین در چنین شرایطی 29 درصد از کل شهروندان اردبیلی بی­خانمان می­شوند.
نتیجه ­گیری: شهر اردبیل در محدوده خطر لرزه­ای متوسط تا زیاد قرار دارد که در آئین­نامه لرزه­ای فعلی کشور با زلزله­ای خاص با بزرگی VII  و شتاب مربوط به آن 04/0 گرم شناسایی شده است. شهر و اطراف آن از خطر لرزه‌ای نسبتاً بالایی برخوردار است که عمدتاً به دلیل جمعیت زیاد و ساختمان‌های قدیمی و آسیب‌پذیر است. آسیب­پذیری ساختمان­ها در اردبیل میانگین مقدار 59/0 را برای ساختمان­های بتنی و 93/0 را برای ساختمان­های بنایی نشان می­دهد. بنابراین پیش­بینی می­شود که سازه­های بنایی دارای درجه آسیب بالاتری باشند، زیرا الگوی آسیب­پذیری به الگوی آسیب منتقل می­شود. شاخص آسیب­پذیری مناطق 1 (950/0) و 3 (850/0) بالاتر از سایر مناطق است. از سوی دیگر، با توجه به افزایش زیرساخت­ها و خدمات در مناطق، یک تا چهار عنصر آسیب­پذیر به­طور مداوم در حال افزایش است. بنابراین، تنها راه کاهش خطر لرزه­ای با رویکرد کاهش آسیب­پذیری، اقدامات سخت­گیرانه مقررات لرزه­ای و افزایش آگاهی عمومی است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Earthquake risk scenarios in urban areas (Case study: Ardabil city)

نویسنده [English]

  • Rasoul Samadzadeh
Department of Geography, Ardabil Branch, Islamic Azad University, Ardabil, Iran
چکیده [English]

Introduction: Urban-scale seismic risk assessment is an essential activity to assess the potential consequences of large earthquakes. This method includes a series of systematic research steps that begin with the identification of seismic hazard, continue with the assessment of the vulnerability of buildings and end with the development of hazard plans and appropriate mitigation plans. The Impact of Seismic Scenarios on the Ardabil City, the ultimate goal of this study is to provide up-to-date information on the seismic vulnerability assessment of the urban operational plan.
Materials and methods: In this study, a method based on the vulnerability index has been used to assess the expected damage in Ardabil. This method introduces a vulnerability index to display and determine whether a building belongs to a particular vulnerability class. This method uses the mean of quasi-experimental vulnerability functions, which for a given vulnerability index is strongly associated with seismicity and expected damage. Risk analysis for seismic scenarios defined by seismic intensities V, V-VI, VI, VI-VII and VII has been performed to design seismic emergency plans.
Results and Discussion: High vulnerability causes significant direct physical damage to buildings, even for low-intensity earthquakes. As a result, the expected physical damage in the case of moderate earthquakes is significant. For a magnitude V earthquake, the damage is not expected to be significant, but for a magnitude VII scenario, all five areas and the dilapidated textures within them will experience a level of damage that is slightly higher. Among the five urban areas, Region 2 will have the greatest economic impact due to its high-altitude density, and will cost approximately 261 billion rials for the VII intensity scenario. The economic impact of the earthquake for the five regions is from 101 billion rials for the earthquake with magnitude V-VI to 844 for the earthquake with magnitude VII. Due to the impact of a seismic crisis, there is a significant volume of expected debris production. In addition, under such circumstances, 29% of the total citizens of Ardabil become homeless.
Conclusion: The city of Ardabil is in the range of moderate to high seismic hazard, which in the current seismic norm of the country has been identified by a specific earthquake with a magnitude of VII and a related acceleration of 0.04g. The city and its environs have a relatively high seismic risk, mainly due to the large population and old and vulnerable buildings. Vulnerability of buildings in Ardabil shows an average value of 0.59 for concrete buildings and 0.93 for masonry buildings. Therefore, masonry structures are predicted to have a higher degree of damage, because the pattern of vulnerability is transferred to the pattern of damage. The vulnerability index of regions 1 (0.950) and 3 (0.850) is higher than other regions. On the other hand, due to the increase in infrastructure and services in areas, one to four vulnerable elements are constantly increasing. Therefore, the only way to reduce seismic risk with a vulnerability reduction approach is through strict measures of seismic regulations and raising public awareness.

کلیدواژه‌ها [English]

  • Physical vulnerability
  • Ardabil
  • Vulnerability index
  • Risk scenario
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