مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

بررسی پارامتر لرزهخیزی b-value و بعد فرکتال لرزهخیزی (DC-value) در رابطه با زمین لرزه سال 2017 سرپل ذهاب-ازگله

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 کارشناسی ارشد، گروه آموزش فیزیک، دانشگاه فرهنگیان، تهران، ایران
2 استادیار، دانشکده علوم پایه، دانشگاه اراک، اراک، ایران
چکیده
زمین‌لرزه 3/7 ریشتری سرپل‌ذهاب که در تاریخ ۱۲ نوامبر ۲۰۱۷ در منطقه زاگرس رخ داد، نیاز به تحلیل‌های دقیق لرزه‌خیزی در این پهنه فعال تکتونیکی را برجسته می‌کند. در پژوهش حاضر، تغییرات مکانی-زمانی پارامترهای b-value و DC-value در ناحیه اطراف این رخداد، با استفاده از کاتالوگ یکپارچه زمین‌لرزه‌های ثبت‌شده توسط مرکز لرزه‌نگاری کشوری (IRSC) در بازه ۱ ژانویه ۲۰۰۶ تا ۳۱ اکتبر ۲۰۲۴، مورد بررسی قرار گرفت. نتایج نشان می‌دهد که در بخش‌های تکتونیکی فعال، b-value بین 4/0 تا 4/1 متغیر بوده است؛ کاهش این پارامتر در مجاورت گسل پیش از زمین‌لرزه اصلی، بیانگر تجمع تنش و احتمال وقوع گسیختگی قریب‌الوقوع می‌باشد. در مقابل، افزایش DC-value نشانگر ناهمگونی ساختار گسل و پیچیدگی مکانیزم شکستگی در آستانه تنش است. بلافاصله پس از رخداد اصلی، افزایش قابل‌توجه b-value نشان‌دهنده آزادسازی تنش از طریق پس‌لرزه‌های کوچک و کاهش DC-value مشاهده می‌شود. تحلیل زمانی b-value روند کاهشی پیش از رخداد و روند افزایشی پس از آن را شناسایی می‌کند که ناشی از بازتوزیع تنش در ساختار زمین‌شناسی منطقه محسوب می‌شود. همچنین، مقدار پایین b-value (کمتر از 5/0) در عمق‌های ۱۰ تا ۲۰ کیلومتر، تمرکز تنش را در این محدوده عمقی تأیید می‌کند. یافته‌های به‌دست آمده، نقش مکمل b-value و DC-value را در توصیف رفتار لرزه‌ای، ارزیابی تکامل گسل و فرآیندهای زمین‌ساختی در گسل‌های معکوس، تراستی و امتدادلغز منطقه زاگرس به‌وضوح بیان می‌کنند. نتایج بدست آمده ابزاری بسیار کلیدی در ارزیابی خطر لرزه‌ای در مناطق تکتونیکی می باشند.
کلیدواژه‌ها
موضوعات

عنوان مقاله English

Investigation of the seismic parameter b value and the fractal seismicity dimension (Dc value) in relation to the 2017 Sarpol Zahab–Ezgeleh earthquake

نویسندگان English

Muhammed Hossein Mousavi 1
Amir Talebi 2
Faegheh Mina Araghi 2
1 M.Sc., Department of Physics Education, Farhangian University, Tehran, Iran
2 Assistant Professor, Department of Physics, Faculty of Science, Arak University, Arak, Iran
چکیده English

The 7.3 magnitude Serpel Zahab earthquake, which occurred on November 12, 2017, in the Zagros region, underscores the need for thorough seismic hazard analyses in this active tectonic zone. In the present study, the spatiotemporal variations of the seismic parameters b-value and DC-value in the vicinity of the earthquake were examined using an integrated earthquake catalog recorded by the National Seismological Center (IRSC) during the period from January 1, 2006, to October 31, 2024. The results indicate that in the active tectonic segments, the b-value varied between 0.4 and 1.4, a reduction in this parameter adjacent to the fault prior to the mainshock suggests stress accumulation and the potential for an imminent rupture. In contrast, an increase in the DC-value reflects enhanced heterogeneity in the fault structure and a more complex fracture mechanism nearing failure. Immediately following the main event, a significant increase in the b-value was observed, indicative of stress release through smaller aftershocks, alongside a decrease in the DC-value. The temporal analysis of the b-value revealed a decreasing trend before and a pronounced increasing trend after the earthquake, attributable to stress redistribution within the region’s geological framework. Additionally, low b-value values (less than 0.5) at depths between 10 and 20 kilometers confirm a concentration of stress within this depth interval. These findings clearly demonstrate the complementary roles of the b-value and DC-value in characterizing seismic behavior, assessing fault evolution, and understanding the tectonic processes in reverse, strike-slip, and extensional faults of the Zagros region. The obtained results serve as a crucial tool for evaluating seismic hazard in tectonically active areas.

کلیدواژه‌ها English

b-value
DC-value
Sarpol Zahab
seismotectonics
Zagros
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دوره 20، شماره 4
مرداد و شهریور 1405
صفحه 1-16

  • تاریخ دریافت 02 تیر 1404
  • تاریخ بازنگری 25 شهریور 1404
  • تاریخ پذیرش 03 آبان 1404
  • تاریخ اولین انتشار 26 اردیبهشت 1405
  • تاریخ انتشار 01 مرداد 1405