تحلیل مکانی و زمانی زمین لرزه های ایران در طی سال های 1907 تا 2023 (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
موقعیت زمین ساختی ایران سبب شده است تا این کشور پتانسیل لرزه خیزی بالایی داشته باشد. با توجه به اینکه زمین لرزه با خسارات جانی و مالی زیادی همراه است و مطالعه در این زمینه دارای اهمیت بالایی است، در این پژوهش به تحلیل مکانی و زمانی زمین لرزه های رخ داده در ایران پرداخته شده است. این پژوهش بر مبنای روش های کمی است. مهم ترین داده های پژوهش، لایه رقومی ارتفاعی 30 متر SRTM، لایه رقومی گسل های ایران و همچنین اطلاعات مربوط به کانون زمین لرزه های ثبت شده در ایران در طی سال های 1907 تا 2023 (1402-1286) است که از سایت USGS تهیه شده است. مهم ترین ابزارهای پژوهش ArcGIS و SPSS بوده است. با توجه به اهداف مورد نظر، در این پژوهش ابتدا به آنالیز مکانی و سپس آنالیز زمانی زمین لرزه های رخ داده پرداخته شده است. بر اساس نتایج حاصله، در طی دوره زمانی موردمطالعه، 7139 زمین لرزه با بزرگای بیش از 3 ریشتر در ایران ثبت شده است که 12 زمین لرزه بیش از 7 ریشتر بزرگا داشته اند (بر این اساس حدوداً هر 10 سال یک بار شاهد یک زمین لرزه بیش از 7 ریشتری در ایران بوده ایم). نتایج آنالیز مکانی و تحلیل فضایی زمین لرزه های رخ داده نشان داده است که از نظر کمی و تعداد کانون های زمین لرزه، مناطق جنوب غربی کشور دارای بیش ترین پتانسیل لرزه خیزی هستند ولی از نظر زمین لرزه های با بزرگای بالای 7 ریشتر، مناطق شرقی و شمال غربی کشور دارای پتانسیل بالاتری هستند. همچنین مناطق مرکزی کشور، خصوصاً مناطق مجاور شهر اصفهان، دارای کم ترین پتانسیل لرزه خیزی هستند. نتایج آنالیز زمانی زمین لرزه های رخ داده نیز نشان داده است که بیش ترین تعداد زمین لرزه های رخ داده مربوط به ماه های فروردین و اردیبهشت و ساعات اولیه بامداد بوده است.Spatial and temporal analysis of earthquakes in Iran During the years 1907 to 2023
Extended Abstract
Introduction
The geological situation of Iran and the presence of active faults have resulted in frequent earthquakes occurring in Iran every year. In some cases, large earthquakes have caused significant human and financial losses. Earthquake risk has always been a major concern due to the substantial damage it can cause, but unfortunately, no method has yet been developed to accurately predict the time of its occurrence. This challenge has led to the adoption of statistical methods for approximate earthquake prediction. Given the importance of earthquakes and Iran's high seismic potential, this research focuses on the spatial and temporal analysis of earthquakes that have occurred in Iran. As no comprehensive studies have been conducted on earthquake spatial and temporal analysis, the purpose of this research is to assess the earthquake situation in Iran and identify high-risk areas. Additionally, another aim of this research is to address questions and rumors about the timing of earthquakes at different hours of the day and night. To achieve these objectives, the analysis uses data on earthquake epicenters recorded in Iran between the years 1286 to 1402 (1907 to 2023).
Material and Methods
This research is based on quantitative methods. The key datasets include the SRTM 30-meter digital elevation model, a digital layer of Iran's faults, and information about earthquake epicenters recorded in Iran from 1286 to 1402 (1907 to 2023), sourced from the USGS website. The primary research tools are ArcGIS (for map preparation) and SPSS (for data analysis). According to the research objectives, the study was conducted in two main stages. In the first stage, after gathering statistical data on earthquake epicenters, the spatial analysis of earthquakes was performed by examining magnitude, political divisions, and proximity to major faults. In the second stage, temporal analysis was conducted by evaluating earthquakes across different months and times of the day and night.
Discussion and Results
In this research, earthquakes that occurred in Iran from 1286 to 1402 were analyzed. The results revealed that during the study period, 7139 earthquakes with a magnitude greater than 3 Richter were recorded in Iran, including 12 earthquakes exceeding 7 Richter. This indicates that, on average, an earthquake with a magnitude greater than 7 occurs approximately once every 10 years. The spatial analysis of earthquakes based on political divisions showed that the highest number of earthquake centers were located in the provinces of Hormozgan, Fars, and Kerman, where 1187, 1175, and 796 earthquakes with magnitudes greater than 3 Richter were recorded, respectively. Conversely, the provinces of Alborz, Markazi, and Qom recorded the lowest number of earthquake centers, with 4, 8, and 11 centers, respectively.
The spatial analysis of earthquakes in relation to major faults indicated that the highest earthquake density occurred near the Zagros fault and the Kazeroon fault. Additionally, experts observed that earthquakes with magnitudes greater than 6 Richter were more frequently associated with these faults.
Conclusion
The results of the spatial analysis of earthquakes showed that, in terms of quantity and the number of earthquake foci, the southwestern regions of the country have the highest seismic potential. However, regarding high-magnitude earthquakes (7 Richter), the eastern and northwestern regions of the country exhibit the highest potential. The results also indicate that while the Zagros fault has caused numerous earthquakes, the Nayband fault has played a significant role in high-magnitude earthquakes. Temporal analysis was also conducted, showing that the majority of earthquakes occurred during the months of May and April, with a general decrease in earthquake frequency from May to February. Analysis of the time of occurrence revealed that the highest number of earthquakes occurred between 24:00 and 6:00, while the fewest occurred between 6:00 and 12:00. Overall, earthquake frequency increased from early afternoon until midnight and decreased thereafter until noon. The findings suggest that the early hours of the morning, along with the months of May and April, exhibit the highest earthquake frequency.
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