چکیده:
ماهیت پیچیده فرایندهای زمینساختی عامل ایجاد توپوگرافی و همچنین ابعاد مناظر طبیعی زمین را نمیتوان با ساختارهای کلاسیک، مانند هندسه اقلیدسی یا منطق ارسطویی، ارزیابی نمود. برای این منظور، تحلیل فرکتالی آبراههها و شکستگیها با استفاده از روش شمارش جعبهای برای تعیین بلوغ ساختاری زاگرس شمالغرب انجام گرفت. همچنین با کمک معیارهای مرتبط با مورفوتکتونیک، پتانسیل فعالیت تکتونیکی منطقه با روش عدم قطعیت فازی مشخص و نتایج این دو روش با کانونهای سطحی زلزله مقایسه شدند. مناطق دارای بعد فرکتالی بالای گسل و پایین زهکشی فعالیت تکتونیکی بیشتری دارند. طبق این تحقیق، محدودۀ A یعنی غرب کرمانشاه، دارای بالاترین بعد فرکتالی (32/ 1) گسل و بعد فرکتالی کمتر برای شبکۀ زهکشی (432/ 1) است و شواهد لرزهای ازجمله زلزلۀ اخیر کرمانشاه با 3/ 7 ریشتر نیز پویا بودن آن را تایید میکند. محدودۀ E که رو به فروافتادگی دزفول است، کمترین بعد فرکتالی گسل (07/ 1) و بیشترین بعد فرکتالی شبکۀ زهکشی (470/ 1) را دارا است. با این حال گسلهای مدفون نقش مهمی در تولید زلزله در شمال این محدوده دارند. همپوشانی مربعهای فرکتالی با گاماهای مختلف در مدل فازی تا حد زیادی تاییدکنندۀ نتایج بود و محدودۀ A در این مدل نیز بالاترین پتانسیل فعالیت تکتونیکی را نشان میدهد.
Introduction
In order to tectonic analysis northwestern Zagros, we have used fractal geometry against classic geometry and fuzzy logic instead of Aristotelian classic logic to evaluate natural landscapes with non-integer dimension and the complex nature of tectonic processes. The fractal dimension (FD) has been applied to determine anomaly or normality of surface rupture (faults) pattern in association with drainage network that can show the maturity of structures. In other hand, uncertainty of fuzzy logic has been applied to specify the potential of tectonic activity by using morphotectonic factors. At the end, we have compared results of these two methods with surface epicenters of earthquakes.
Methodology
To calculate the FD of faults and drainage network using box-counting, the area was divided to 6 boxes that contain main fault trends horizontally and vertically. In fractal method each box is covered by several network (grid) that their side length (quantity of Size) is decreased at every grid level. Then the relation between reciprocal of side length and boxes containing linear feature (quantity of Number) was drawn Logarithmically as a linear regression that shows FD. In fuzzy model, six main effective factors were determined and 12 layers were produced base on their importance in tectonic analysis. The membership degree of these layers’ effective parts by fuzzy functions were determined and then they were overlaid by fuzzy operators like gamma with different powers.
Results and Discussion
Calculating number-size quantity using box-counting method for faults and drainage network shows both partial and overall FD changes. As partial changes are close, yjey indicate the existence of the self-similarity components. Based on partial FD, there are three communities: back ground with FD larger than slope of linear regression, threshold community with repeating component, and anomaly community with FD value more than three. Based on overall FD, development of faults and drainage network have not entered to chaos phase. The comparison of mean value of fuzzy zoning with different gamma powers for each box indicates that 0.7 power of gamma has the most correlation with overall FD of boxes.
Conclusion
Areas of high value of FD for faults and low value for drainage network are more tectonically active. Here the box labeled A which represent western parts of Kermanshah in folded Zagros, has the highest FD value of faults (1.32) and lower FD value of drainage network (1.432). Epicenter evidences of earthquakes for example 7.3 magnitude earthquake of Ezgeleh, confirm the FD results; whereas, the box labeled E near Dezful Embayment shows the lowest FD value of faults (1.07) and highest FD value of drainage network (1/470). Overlaying fractal boxes (A to F) with fuzzy exports (gamma 0.7) are in line with these results and represent more potential of tectonic activity for northwestern parts of area (box A).
Keywords: Tectonic, Northwestern Zagros, Fractal, Fuzzy.Introduction
In order to tectonic analysis northwestern Zagros, we have used fractal geometry against classic geometry and fuzzy logic instead of Aristotelian classic logic to evaluate natural landscapes with non-integer dimension and the complex nature of tectonic processes. The fractal dimension (FD) has been applied to determine anomaly or normality of surface rupture (faults) pattern in association with drainage network that can show the maturity of structures. In other hand, uncertainty of fuzzy logic has been applied to specify the potential of tectonic activity by using morphotectonic factors. At the end, we have compared results of these two methods with surface epicenters of earthquakes.
Methodology
To calculate the FD of faults and drainage network using box-counting, the area was divided to 6 boxes that contain main fault trends horizontally and vertically. In fractal method each box is covered by several network (grid) that their side length (quantity of Size) is decreased at every grid level. Then the relation between reciprocal of side length and boxes containing linear feature (quantity of Number) was drawn Logarithmically as a linear regression that shows FD. In fuzzy model, six main effective factors were determined and 12 layers were produced base on their importance in tectonic analysis. The membership degree of these layers’ effective parts by fuzzy functions were determined and then they were overlaid by fuzzy operators like gamma with different powers.
Results and Discussion
Calculating number-size quantity using box-counting method for faults and drainage network shows both partial and overall FD changes. As partial changes are close, yjey indicate the existence of the self-similarity components. Based on partial FD, there are three communities: back ground with FD larger than slope of linear regression, threshold community with repeating component, and anomaly community with FD value more than three. Based on overall FD, development of faults and drainage network have not entered to chaos phase. The comparison of mean value of fuzzy zoning with different gamma powers for each box indicates that 0.7 power of gamma has the most correlation with overall FD of boxes.
Conclusion
Areas of high value of FD for faults and low value for drainage network are more tectonically active. Here the box labeled A which represent western parts of Kermanshah in folded Zagros, has the highest FD value of faults (1.32) and lower FD value of drainage network (1.432). Epicenter evidences of earthquakes for example 7.3 magnitude earthquake of Ezgeleh, confirm the FD results; whereas, the box labeled E near Dezful Embayment shows the lowest FD value of faults (1.07) and highest FD value of drainage network (1/470). Overlaying fractal boxes (A to F) with fuzzy exports (gamma 0.7) are in line with these results and represent more potential of tectonic activity for northwestern parts of area (box A).
Keywords: Tectonic, Northwestern Zagros, Fractal, Fuzzy.
خلاصه ماشینی:
طبق این تحقیق ، محدودۀ A یعنی غرب کرمانشاه ، دارای بالاترینُ بعد فرکتالی (١/٣٢) گسل وُ بعد فرکتالی کمتر برای شبکۀ زهکشی (١/٤٣٢) است و شواهد لرزه ای ازجمله زلزلۀ اخیر کرمانشاه با ٧/٣ ریشتر نیز پویا بودن آن را تأیید میکند.
بر این اساس ، خطوط الگوی زهکشی و بردارهای گسلی محدودۀ زاگرس شمال غرب را استخراج نموده و با استفاده از روش فرکتالی بهنجاری یا نابهنجاری الگوی گسیختگی پوسته با شبکه های آبراهه ای که بیانگر پویایی یا آرامش تکتونیکی است ، بررسی نموده ایم .
صدر و همکاران (١٣٩٧)، ابعاد فرکتالی شکستگی ها و آبراهه های جنوب غرب قزوین را به روش فرکتال مورد بررسی قرار دادند و دریافتند کهُ بعد فرکتالی بالاتر مؤید مناطقی با فعالیت نسبی بیشتر بوده و مشاهدات میدانی نیز در تأیید آن است .
Fuzzy Logic گسل های اصلی زاگرس و گسل های جبهۀ کوهستان را تحت پوشش قرار دهند تقسیم نموده و ُبعد فرکتالی شبکۀ زهکشی و گسل ها برای جعبه های مختلف محاسبه و با نتایج مدل فازی و درنهایت هر دو این روش ها با داده های زلزلۀ منطقه مورد مقایسه قرار گرفت .
The Egyptian Journal of Remote Sensing and Space Science, In press, DOI.
“Investigation of the Role of Active Tectonic Structures in Fractal Dimensions of Fractures and Waterways of Hasan Abad Fault (Southwest of Qazvin)”.
Fractal and Chaos in Geology and Geophysics, Cambridge University Press.